Related
I Have An Array,for example
string[] stArr= new string[5] { "1#3", "19#24", "10#12", "13#18", "20#21" };
i want to sort this array on
3-1=2;
24-19=5;
12-10=2;
18-13=5;
21-20=1;
and the sorting result should be like
string[] stArr= new string[5] { "20#21", "1#3", "10#12", "13#18", "20#21" };
I have to find the solution for all possible cases.
1>length of the array is not fixed(element in the array)
2>y always greater than x e.g x#y
3> i can not use list
You can use LINQ:
var sorted = stArr.OrderBy(s => s.Split('#')
.Select(n => Int32.Parse(n))
.Reverse()
.Aggregate((first,second) => first - second));
For Your Case:
stArr = stArr.OrderBy(s => s.Split('#')
.Select(n => Int32.Parse(n))
.Reverse()
.Aggregate((first,second) => first - second)).ToArray();
try this
string[] stArr = new string[5] { "1#3", "19#24", "10#12", "13#18", "20#21" };
Array.Sort(stArr, new Comparison<string>(compare));
int compare(string z, string t)
{
var xarr = z.Split('#');
var yarr = t.Split('#');
var x1 = int.Parse(xarr[0]);
var y1 = int.Parse(xarr[1]);
var x2 = int.Parse(yarr[0]);
var y2 = int.Parse(yarr[1]);
return (y1 - x1).CompareTo(y2 - x2);
}
Solving this problem is identical to solving any other sorting problem where the order is to be specified by your code - you have to write a custom comparison method, and pass it to the built-in sorter.
In your situation, it means writing something like this:
private static int FindDiff(string s) {
// Split the string at #
// Parse both sides as int
// return rightSide-leftSide
}
private static int CompareDiff(string a, string b) {
return FindDiff(a).CompareTo(FindDiff(b));
}
public static void Main() {
... // Prepare your array
string[] stArr = ...
Array.Sort(stArr, CompareDiff);
}
This approach uses Array.Sort overload with the Comparison<T> delegate implemented in the CompareDiff method. The heart of the solution is the FindDiff method, which takes a string, and produces a numeric value which must be used for comparison.
you can try the following ( using traditional way)
public class Program
{
public static void Main()
{
string[] strArr= new string[5] { "1#3", "19#24", "10#12", "13#18", "20#21" };
var list = new List<Item>();
foreach(var item in strArr){
list.Add(new Item(item));
}
strArr = list.OrderBy(t=>t.Sort).Select(t=>t.Value).ToArray();
foreach(var item in strArr)
Console.WriteLine(item);
}
}
public class Item
{
public Item(string str)
{
var split = str.Split('#');
A = Convert.ToInt32(split[0]);
B = Convert.ToInt32(split[1]);
}
public int A{get; set;}
public int B{get; set;}
public int Sort { get { return Math.Abs(B - A);}}
public string Value { get { return string.Format("{0}#{1}",B,A); }}
}
here a working demo
hope it will help you
Without LINQ and Lists :) Old School.
static void Sort(string [] strArray)
{
try
{
string[] order = new string[strArray.Length];
string[] sortedarray = new string[strArray.Length];
for (int i = 0; i < strArray.Length; i++)
{
string[] values = strArray[i].ToString().Split('#');
int index=int.Parse(values[1].ToString()) - int.Parse(values[0].ToString());
order[i] = strArray[i].ToString() + "," + index;
}
for (int i = 0; i < order.Length; i++)
{
string[] values2 = order[i].ToString().Split(',');
if (sortedarray[int.Parse(values2[1].ToString())-1] == null)
{
sortedarray[int.Parse(values2[1].ToString())-1] = values2[0].ToString();
}
else
{
if ((int.Parse(values2[1].ToString())) >= sortedarray.Length)
{
sortedarray[(int.Parse(values2[1].ToString())-1) - 1] = values2[0].ToString();
}
else if ((int.Parse(values2[1].ToString())) < sortedarray.Length)
{
sortedarray[(int.Parse(values2[1].ToString())-1) + 1] = values2[0].ToString();
}
}
}
for (int i = 0; i < sortedarray.Length; i++)
{
Console.WriteLine(sortedarray[i]);
}
Console.Read();
}
catch (Exception ex)
{
throw;
}
finally
{
}
I've got a Problem with my Console Output I receive always exceptions and can't fix the bug the solution already worked but the stack grows from top to bottom, so I tried to sort my Elements by
Whitespace.Count to reverse that order hope you can help me, here is my code:
public class TvH
{
#region
IDictionary<string, int> towerMapping = new Dictionary<string, int>()
{
{"Start", 0}, {"Mitte", 1}, {"Ziel", 2}
};
private string emptyTower = " | ";
private int turns = 0;
Stack<string>[] towers;
Dictionary<int, string> discs = new Dictionary<int, string>()
{
{1, "-----|-----"},
{2, " ----|---- "},
{3, " ---|--- "},
{4, " --|-- "},
{5, " -|- "}
};
#endregion
public TvH(int towerCount)
{
towers = new Stack<string>[towerCount];
initializeTowers();
}
private void initializeTowers()
{
for (int i = 0; i < towers.Length; i++)
{
towers[i] = new Stack<string>();
}
for (int i = 1; i <= discs.Count; i++)
{
towers[0].Push(discs[i]);
towers[1].Push(emptyTower);
towers[2].Push(emptyTower);
}
}
public void bewegeScheibe(int n, string a, string b, string c)
{
if (n > 0)
{
bewegeScheibe(n - 1, a, c, b);
turns++;
Console.Write("\nZug # ");
if (turns < 10)
{
Console.Write("0");
}
Console.WriteLine("{0} Disc # {1} {2} --> {3}\n", turns, n, a, c);
move(a, c);
bewegeScheibe(n - 1, b, a, c);
}
}
private void move(string start, string target)
{
var element = towers[towerMapping[start]].Pop();
towers[towerMapping[target]].Push(element);
printContent();
}
private void printContent()
{
IList<string> t1 = prepairTowerForPrint(towers[0].GetEnumerator());
IList<string> t2 = prepairTowerForPrint(towers[1].GetEnumerator());
IList<string> t3 = prepairTowerForPrint(towers[2].GetEnumerator());
int i = 0;
while (i < discs.Count)
{
object ob1 = t1[i];
object ob2 = t2[i];
object ob3 = t3[i];
Console.WriteLine("\t{0}\t{1}\t{2}", ob1, ob2, ob3);
i++;
}
}
private IList<string> prepairTowerForPrint(Stack<string>.Enumerator enumerator)
{
IList<string> towerList = new List<string>();
while (enumerator.MoveNext())
{
towerList.Add(TryReadNext(enumerator));
}
towerList = towerList.OrderByDescending(scheiben => scheiben.Count(Char.IsWhiteSpace)).ToList();
return towerList;
}
private string TryReadNext(IEnumerator ce)
{
if (ce.MoveNext())
{
return (string)ce.Current;
}
else
{
return emptyTower;
}
}
}
thank you very much
The problem is that you assume that each stack always has five discs, yet in the method move you pop an element from one and push it on another. Hence the error.
So you'd need to remove one element from towers[towerMapping[target]] and add one to towers[towerMapping[start]].
Can I also do a little code review?
Why is discs a dictionary? It would make for more sense to make it a List() and simply loop through it:
List<string> discs = new List<string>()
{
"-----|-----",
" ----|---- ",
" ---|--- ",
" --|-- ",
" -|- "
};
foreach(var dics in discs)
{
towers[0].Push(disc);
towers[1].Push(emptyTower);
towers[2].Push(emptyTower);
}
Why do you do towers = new Stack<string>[towerCount]; in the TvH constructor instead of in the method called initializeTowers()?
The method prepairTowerForPrint contains a typo, the verb is to prepare.
Method names in German are a bad idea, IMHO. Also, method names should be PascalCase.
The only public method is bewegeScheibe() but it's parameters are actually part of the TvH class: "Start", "Mitte", "Ziel". It's first parameter is int n, which says absolutely nothing; I only figured out what string a, string b, string c were expected to be by reading the code.
Ok I solved another way, here's the code if anybody needs
using System;
using System.Collections;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
namespace TuermeVonHanoi
{
public class TvH
{
#region
IDictionary<string, int> towerMapping = new Dictionary<string, int>()
{
{"start", 0}, {"middle", 1}, {"target", 2}
};
private string emptyTower = " | ";
private int turns = 0;
Stack<string>[] towers;
IList<string> discs = new List<string>()
{
{"-----|-----"},
{" ----|---- "},
{" ---|--- "},
{" --|-- "},
{" -|- "}
};
#endregion
public TvH(int towerCount)
{
towers = new Stack<string>[towerCount];
initializeTowers();
}
private void initializeTowers()
{
for (int i = 0; i < towers.Length; i++)
{
towers[i] = new Stack<string>();
}
foreach (var d in discs)
{
towers[0].Push(d);
}
}
public void moveAlgorithmic(int n, string a, string b, string c)
{
if (n > 0)
{
moveAlgorithmic(n - 1, a, c, b);
++turns;
Console.Write("\nturn # ");
if (turns < 10)
{
Console.Write("0");
}
Console.WriteLine("{0} disc # {1} {2} --> {3}\n", turns, n, a, c);
moveVisual(a, c);
moveAlgorithmic(n - 1, b, a, c);
}
}
private void moveVisual(string start, string target)
{
var element = towers[towerMapping[start]].Pop();
towers[towerMapping[target]].Push(element);
printContent();
}
private void printContent()
{
IList<string> t1 = prepareTowerForPrint(towers[0].GetEnumerator());
IList<string> t2 = prepareTowerForPrint(towers[1].GetEnumerator());
IList<string> t3 = prepareTowerForPrint(towers[2].GetEnumerator());
int i = 0;
while (i < discs.Count)
{
object ob1 = t1[i];
object ob2 = t2[i];
object ob3 = t3[i];
Console.WriteLine("\t{0}\t{1}\t{2}", ob1, ob2, ob3);
++i;
}
}
private IList<string> prepareTowerForPrint(Stack<string>.Enumerator enumerator)
{
IList<string> towerList = new List<string>();
int count = 0;
while (enumerator.MoveNext())
{
++count;
towerList.Add(enumerator.Current);
}
int toPush = discs.Count - count;
for (int i = 0; i < toPush; i++ )
{
towerList.Add(emptyTower);
}
if (toPush != 0 || toPush != 1)
{
towerList = towerList.OrderByDescending(d => d.Count(Char.IsWhiteSpace)).ToList();
}
return towerList;
}
}
}
instead of initializing all 3 stacks we calculate how many empty pin elements have to be printed out for every stack
if I have two array
A:[A,B]
B:[1,2,3]
how can I create a string List like [A_1, A_2, A_3, B_1, B_2, B_3]
the number of array is not regular, it's maybe have 3 more
A:[A,B]
B:[1,2,3]
C:[w,x,y,z]
D:[m,n]
E:[p,q,r]
can I use recursive to solve it?
So, we define a functions Mergethat takes lists of list of stings and merges them into the string enumerable you want
static void Main(string[] args)
{
var a = new[] { "A", "B" };
var b = new[] { "1", "2", "3" };
var c = new[] { "x", "y", "z", "w" };
var result = Merge(a, b, c);
foreach (var r in result)
{
Console.WriteLine(r);
}
}
public static IList<string> Merge(params IEnumerable<string>[] lists)
{
return Merge((IEnumerable<IEnumerable<string>>) lists);
}
public static IList<string> Merge(IEnumerable<IEnumerable<string>> lists)
{
var retval = new List<string>();
var first = lists.FirstOrDefault();
if (first != null)
{
var result = Merge(lists.Skip(1));
if (result.Count > 0)
{
foreach (var x in first)
{
retval.AddRange(result.Select(y => string.Format("{0}_{1}", x, y)));
}
}
else
{
retval.AddRange(first);
}
}
return retval;
}
we can also improve this, if you use Lists as inputs
public static IList<string> Merge(params IList<string>[] lists)
{
return Merge((IList<IList<string>>) lists);
}
public static IList<string> Merge(IList<IList<string>> lists, int offset = 0)
{
if (offset >= lists.Count)
return new List<string>();
var current = lists[offset];
if (offset + 1 == lists.Count) // last entry in lists
return current;
var retval = new List<string>();
var merged = Merge(lists, offset + 1);
foreach (var x in current)
{
retval.AddRange(merged.Select(y => string.Format("{0}_{1}", x, y)));
}
return retval;
}
This is simple iterating over n-ary dimension - no need for recursion for that, just array to store indexes.
static void Iterate(int[] iterators, ArrayList[] arrays) {
for (var j = iterators.Length - 1; j >= 0; j--) {
iterators[j]++;
if (iterators[j] == arrays[j].Count) {
if (j == 0) {
break;
}
iterators[j] = 0;
} else {
break;
}
}
}
static IList<string> Merge(ArrayList[] arrays) {
List<string> result = new List<string>();
int[] iterators = new int[arrays.Length];
while (iterators[0] != arrays[0].Count) {
var builder = new StringBuilder(20);
for(var index = 0; index < arrays.Length; index++) {
if (index > 0) {
builder.Append("_");
}
builder.Append(arrays[index][iterators[index]]);
}
result.Add(builder.ToString());
Iterate(iterators, arrays);
}
return result;
}
static void Main(string[] args) {
var list1 = new ArrayList();
var list2 = new ArrayList();
var list3 = new ArrayList();
list1.Add(1);
list1.Add(2);
list2.Add("a");
list2.Add("b");
list3.Add("x");
list3.Add("y");
list3.Add("z");
var result = Merge(new[] { list1, list2, list3 });
}
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
namespace arrconn {
class Program {
static string[] conn(params Array[] arrs) {
if(arrs.Length == 0) return new string[0];
if(arrs.Length == 1) {
string[] result = new string[arrs[0].Length];
for(int i = 0; i < result.Length; i++)
result[i] = arrs[0].GetValue(i).ToString();
return result; }
else {
string[] result = new string[arrs[0].Length*arrs[1].Length];
for(int i = 0; i < arrs[0].Length; i++)
for(int j = 0; j < arrs[1].Length; j++)
result[i*arrs[1].Length+j] = string.Format("{0}_{1}", arrs[0].GetValue(i), arrs[1].GetValue(j));
if(arrs.Length == 2) return result;
Array[] next = new Array[arrs.Length-1];
next[0] = result; Array.Copy(arrs, 2, next, 1, next.Length-1);
return conn(next);
}
}
static void Main(string[] args) {
foreach(string s in conn(
new string[] { "A", "B" },
new int[] { 1, 2, 3 },
new string[] { "x" },
new string[] { "$", "%", "#" }))
Console.WriteLine(s);
Console.Read();
}
}
}
I guess your input are like this:
var A = ["A","B"];
var B = [1,2,3];
var C = ["x","y","z","w"];
And what you want to obtain is:
var result = ["A_1_x", "A_1_y",...
"A_2_x", "A_2_y",...
"A_3_x", "A_3_y",...
"B_1_x", "B_1_y",...
...
..., "B_3_z", "B_3_w"];
We'll be working with IEnumerable as it will simplify the work for us and give us access to the yield keyword.
First, let's take care of the case where we only concataining two collections:
IEnumerable<string> ConcatEnumerables(IEnumerable<object> first, IEnumerable<object> second)
{
foreach (var x in first)
{
foreach (var y in second)
{
yield return x.ToString() + "_" + y.ToString();
}
}
}
Then we can recursively takle any number of collections:
IEnumerable<string> ConcatEnumerablesRec(IEnumerable<IEnumerable<object>> enums)
{
//base cases
if(!enums.Any())
{
return Enumerable.Empty<string>();
}
if (enums.Count() == 1)
{
return enums.First().Select(o => o.ToString());
}
//recursively solve the problem
return ConcatEnumerables(enums.First(), ConcatEnumerablesRec(enums.Skip(1));
}
Now you just need to call ToArray on the result if you really need an array as your output.
string[] Concatenator(params object[][] parameters)
{
return ConcatEnumerablesRec(parameters).ToArray();
}
This should do the trick. Note that the input sequences do not have to be arrays - they can be any type that implements IEnumerable<>.
Also note that we have to case sequences of value types to sequences of <object> so that they are assignable to IEnumerable<object>.
Here's the compilable Console app demo code:
using System;
using System.Collections.Generic;
using System.Linq;
namespace Demo
{
internal static class Program
{
static void Main()
{
string[] a = {"A", "B", "C", "D"};
var b = Enumerable.Range(1, 3); // <-- See how it doesn't need to be an array.
char[] c = {'X', 'Y', 'Z'};
double[] d = {-0.1, -0.2};
var sequences = new [] { a, b.Cast<object>(), c.Cast<object>(), d.Cast<object>() };
Console.WriteLine(string.Join("\n", Combine("", sequences)));
}
public static IEnumerable<string> Combine(string prefix, IEnumerable<IEnumerable<object>> sequences)
{
foreach (var item in sequences.First())
{
string current = (prefix == "") ? item.ToString() : prefix + "_" + item;
var remaining = sequences.Skip(1);
if (!remaining.Any())
{
yield return current;
}
else
{
foreach (var s in Combine(current, remaining))
yield return s;
}
}
}
}
}
I have a problem here and it seems that my brain has just left the building so I need you guys to help me out. I have an API - method which requires a multidimensional string array. It looks like this:
string[,] specialMacroArray = new string[,] { { "#macro#", "text1" }, {"#secondmacro#", "text2"} }
The contents of the array are calculated throughout my method and therefor I cannot write it like above. So I put the values in a List throughout my code like this:
List<string[]> specialMacros = new List<string[]>();
specialMacros.Add(new string[] { "#macro#", text1 });
specialMacros.Add(new string[] { "#secondmacro#", "text2" });
So far so good... but now I want to convert the list to the multidimensional array. But I can't figure out how.
specialMacroArray = specialMacros.ToArray()
I am using the .NET 3.5 Framework in C#
Thanx in advance
For this case you could just do this:
specialMacroArray = new string[specialMacros.Count, 2];
for (int i = 0; i < specialMacros.Count; i++)
{
specialMacroArray[i, 0] = specialMacros[i][0];
specialMacroArray[i, 1] = specialMacros[i][1];
}
You'll probably have to do it manually. Something like this:
string[,] array = new string[specialMacroArray.Count, 2]
for (int i=0; i<specialMacroArray.Count; ++i)
{
array[i, 0] = specialMacroArray[i][0];
array[i, 1] = specialMacroArray[i][1];
}
This should help you
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
namespace sandbox
{
class Program
{
static void Main(string[] args)
{
List<string[]> specialMacros = new List<string[]>();
specialMacros.Add(new string[] { "#macro#", "text1" });
specialMacros.Add(new string[] { "#secondmacro#", "text2" });
var op = specialMacros.ToMultiDimensionalArray();
Console.Read();
}
}
public static class ArrayHelper
{
public static string[,] ToMultiDimensionalArray(this List<string[]> dt)
{
int col = dt.FirstOrDefault().ToList().Count();
string[,] arr = new string[dt.Count, col];
int r = 0;
foreach (string[] dr in dt)
{
for (int c = 0; c < col; c++)
{
arr[r, c] = dr[c];
}
r++;
}
return arr;
}
}
}
Based on the some of comments I have edited the function but I believe this user can make his own judgement and improve the code if they need to.
public static string[,] ToMultiDimensionalArray(this List<string[]> dt)
{
if (dt.Count == 0 )
throw new ArgumentException("Input arg has no elemets");
int col = dt[0].Count();
string[,] arr = new string[dt.Count, col];
int r = 0;
foreach (string[] dr in dt)
{
for (int c = 0; c < col; c++)
{
arr[r, c] = dr[c];
}
r++;
}
return arr;
}
string[][] specialMacroArray = new string[][] { new string[] { "#macro#", "text1" }, new string[] { "#secondmacro#", "text2" } };
List<string[]> specialMacros = new List<string[]>();
specialMacros.Add(new string[] { "#macro1#", "text1" });
specialMacros.Add(new string[] { "#secondmacro#", "text2" });
specialMacroArray = specialMacros.ToArray();
works fine, no loop is needed... all u have to do is change string[,] to string[][] (that's array of array, initializes in a bit diff way)
updated code:
List<string[,]> specialMacros = new List<string[,]>();
specialMacros.Add(new string[,] { { "#secondmacro#", "text2" }, { "#secondmacro#", "text2" } });
specialMacroArray =specialMacros[0];
I have an ArrayList[] myList and I am trying to create a list of all the permutations of the values in the arrays.
EXAMPLE: (all values are strings)
myList[0] = { "1", "5", "3", "9" };
myList[1] = { "2", "3" };
myList[2] = { "93" };
The count of myList can be varied so its length is not known beforehand.
I would like to be able to generate a list of all the permutations similar to the following (but with some additional formatting).
1 2 93
1 3 93
5 2 93
5 3 93
3 2 93
3 3 93
9 2 93
9 3 93
Does this make sense of what I am trying to accomplish? I can't seem to come up with a good method for doing this, (if any).
Edit:
I am not sure if recursion would interfere with my desire to format the output in my own manner. Sorry I did not mention before what my formatting was.
I want to end up building a string[] array of all the combinations that follows the format like below:
for the "1 2 93" permutation
I want the output to be "val0=1;val1=2;val2=93;"
I will experiment with recursion for now. Thank you DrJokepu
I'm surprised nobody posted the LINQ solution.
from val0 in new []{ "1", "5", "3", "9" }
from val1 in new []{ "2", "3" }
from val2 in new []{ "93" }
select String.Format("val0={0};val1={1};val2={2}", val0, val1, val2)
Recursive solution
static List<string> foo(int a, List<Array> x)
{
List<string> retval= new List<string>();
if (a == x.Count)
{
retval.Add("");
return retval;
}
foreach (Object y in x[a])
{
foreach (string x2 in foo(a + 1, x))
{
retval.Add(y.ToString() + " " + x2.ToString());
}
}
return retval;
}
static void Main(string[] args)
{
List<Array> myList = new List<Array>();
myList.Add(new string[0]);
myList.Add(new string[0]);
myList.Add(new string[0]);
myList[0] = new string[]{ "1", "5", "3", "9" };
myList[1] = new string[] { "2", "3" };
myList[2] = new string[] { "93" };
foreach (string x in foo(0, myList))
{
Console.WriteLine(x);
}
Console.ReadKey();
}
Note that it would be pretty easy to return a list or array instead of a string by changing the return to be a list of lists of strings and changing the retval.add call to work with a list instead of using concatenation.
How it works:
This is a classic recursive algorithm. The base case is foo(myList.Count, myList), which returns a List containing one element, the empty string. The permutation of a list of n string arrays s1, s2, ..., sN is equal to every member of sA1 prefixed to the permutation of n-1 string arrays, s2, ..., sN. The base case is just there to provide something for each element of sN to be concatenated to.
I recently ran across a similar problem in a project of mine and stumbled on this question. I needed a non-recursive solution that could work with lists of arbitrary objects. Here's what I came up with. Basically I'm forming a list of enumerators for each of the sub-lists and incrementing them iteratively.
public static IEnumerable<IEnumerable<T>> GetPermutations<T>(IEnumerable<IEnumerable<T>> lists)
{
// Check against an empty list.
if (!lists.Any())
{
yield break;
}
// Create a list of iterators into each of the sub-lists.
List<IEnumerator<T>> iterators = new List<IEnumerator<T>>();
foreach (var list in lists)
{
var it = list.GetEnumerator();
// Ensure empty sub-lists are excluded.
if (!it.MoveNext())
{
continue;
}
iterators.Add(it);
}
bool done = false;
while (!done)
{
// Return the current state of all the iterator, this permutation.
yield return from it in iterators select it.Current;
// Move to the next permutation.
bool recurse = false;
var mainIt = iterators.GetEnumerator();
mainIt.MoveNext(); // Move to the first, succeeds; the main list is not empty.
do
{
recurse = false;
var subIt = mainIt.Current;
if (!subIt.MoveNext())
{
subIt.Reset(); // Note the sub-list must be a reset-able IEnumerable!
subIt.MoveNext(); // Move to the first, succeeds; each sub-list is not empty.
if (!mainIt.MoveNext())
{
done = true;
}
else
{
recurse = true;
}
}
}
while (recurse);
}
}
You could use factoradics to generate the enumeration of permutations. Try this article on MSDN for an implementation in C#.
This will work no matter how many arrays you add to your myList:
static void Main(string[] args)
{
string[][] myList = new string[3][];
myList[0] = new string[] { "1", "5", "3", "9" };
myList[1] = new string[] { "2", "3" };
myList[2] = new string[] { "93" };
List<string> permutations = new List<string>(myList[0]);
for (int i = 1; i < myList.Length; ++i)
{
permutations = RecursiveAppend(permutations, myList[i]);
}
//at this point the permutations variable contains all permutations
}
static List<string> RecursiveAppend(List<string> priorPermutations, string[] additions)
{
List<string> newPermutationsResult = new List<string>();
foreach (string priorPermutation in priorPermutations)
{
foreach (string addition in additions)
{
newPermutationsResult.Add(priorPermutation + ":" + addition);
}
}
return newPermutationsResult;
}
Note that it's not really recursive. Probably a misleading function name.
Here is a version that adheres to your new requirements. Note the section where I output to console, this is where you can do your own formatting:
static void Main(string[] args)
{
string[][] myList = new string[3][];
myList[0] = new string[] { "1", "5", "3", "9" };
myList[1] = new string[] { "2", "3" };
myList[2] = new string[] { "93" };
List<List<string>> permutations = new List<List<string>>();
foreach (string init in myList[0])
{
List<string> temp = new List<string>();
temp.Add(init);
permutations.Add(temp);
}
for (int i = 1; i < myList.Length; ++i)
{
permutations = RecursiveAppend(permutations, myList[i]);
}
//at this point the permutations variable contains all permutations
foreach (List<string> list in permutations)
{
foreach (string item in list)
{
Console.Write(item + ":");
}
Console.WriteLine();
}
}
static List<List<string>> RecursiveAppend(List<List<string>> priorPermutations, string[] additions)
{
List<List<string>> newPermutationsResult = new List<List<string>>();
foreach (List<string> priorPermutation in priorPermutations)
{
foreach (string addition in additions)
{
List<string> priorWithAddition = new List<string>(priorPermutation);
priorWithAddition.Add(addition);
newPermutationsResult.Add(priorWithAddition);
}
}
return newPermutationsResult;
}
What you are asking for is called the Cartesian Product. Once you know what its called, there are several similar questions on Stack Overflow. They all seem to end up pointing to an answer which ended up written as a blog post:
http://blogs.msdn.com/b/ericlippert/archive/2010/06/28/computing-a-cartesian-product-with-linq.aspx
Non-recursive solution:
foreach (String s1 in array1) {
foreach (String s2 in array2) {
foreach (String s3 in array3) {
String result = s1 + " " + s2 + " " + s3;
//do something with the result
}
}
}
Recursive solution:
private ArrayList<String> permute(ArrayList<ArrayList<String>> ar, int startIndex) {
if (ar.Count == 1) {
foreach(String s in ar.Value(0)) {
ar.Value(0) = "val" + startIndex + "=" + ar.Value(0);
return ar.Value(0);
}
ArrayList<String> ret = new ArrayList<String>();
ArrayList<String> tmp1 ar.Value(0);
ar.remove(0);
ArrayList<String> tmp2 = permute(ar, startIndex+1);
foreach (String s in tmp1) {
foreach (String s2 in tmp2) {
ret.Add("val" + startIndex + "=" + s + " " + s2);
}
}
return ret;
}
Here is a generic recursive function that I wrote (and an overload that may be convenient to call):
Public Shared Function GetCombinationsFromIEnumerables(ByRef chain() As Object, ByRef IEnumerables As IEnumerable(Of IEnumerable(Of Object))) As List(Of Object())
Dim Combinations As New List(Of Object())
If IEnumerables.Any Then
For Each v In IEnumerables.First
Combinations.AddRange(GetCombinationsFromIEnumerables(chain.Concat(New Object() {v}).ToArray, IEnumerables.Skip(1)).ToArray)
Next
Else
Combinations.Add(chain)
End If
Return Combinations
End Function
Public Shared Function GetCombinationsFromIEnumerables(ByVal ParamArray IEnumerables() As IEnumerable(Of Object)) As List(Of Object())
Return GetCombinationsFromIEnumerables(chain:=New Object() {}, IEnumerables:=IEnumerables.AsEnumerable)
End Function
And the equivalent in C#:
public static List<object[]> GetCombinationsFromIEnumerables(ref object[] chain, ref IEnumerable<IEnumerable<object>> IEnumerables)
{
List<object[]> Combinations = new List<object[]>();
if (IEnumerables.Any) {
foreach ( v in IEnumerables.First) {
Combinations.AddRange(GetCombinationsFromIEnumerables(chain.Concat(new object[] { v }).ToArray, IEnumerables.Skip(1)).ToArray);
}
} else {
Combinations.Add(chain);
}
return Combinations;
}
public static List<object[]> GetCombinationsFromIEnumerables(params IEnumerable<object>[] IEnumerables)
{
return GetCombinationsFromIEnumerables(chain = new object[], IEnumerables = IEnumerables.AsEnumerable);
}
Easy to use:
Dim list1 = New String() {"hello", "bonjour", "hallo", "hola"}
Dim list2 = New String() {"Erwin", "Larry", "Bill"}
Dim list3 = New String() {"!", ".."}
Dim result = MyLib.GetCombinationsFromIEnumerables(list1, list2, list3)
For Each r In result
Debug.Print(String.Join(" "c, r))
Next
or in C#:
object list1 = new string[] {"hello","bonjour","hallo","hola"};
object list2 = new string[] {"Erwin", "Larry", "Bill"};
object list3 = new string[] {"!",".."};
object result = MyLib.GetCombinationsFromIEnumerables(list1, list2, list3);
foreach (r in result) {
Debug.Print(string.Join(' ', r));
}
Here is a version which uses very little code, and is entirely declarative
public static IEnumerable<IEnumerable<T>> GetPermutations<T>(IEnumerable<T> collection) where T : IComparable
{
if (!collection.Any())
{
return new List<IEnumerable<T>>() {Enumerable.Empty<T>() };
}
var sequence = collection.OrderBy(s => s).ToArray();
return sequence.SelectMany(s => GetPermutations(sequence.Where(s2 => !s2.Equals(s))).Select(sq => (new T[] {s}).Concat(sq)));
}
class Program
{
static void Main(string[] args)
{
var listofInts = new List<List<int>>(3);
listofInts.Add(new List<int>{1, 2, 3});
listofInts.Add(new List<int> { 4,5,6 });
listofInts.Add(new List<int> { 7,8,9,10 });
var temp = CrossJoinLists(listofInts);
foreach (var l in temp)
{
foreach (var i in l)
Console.Write(i + ",");
Console.WriteLine();
}
}
private static IEnumerable<List<T>> CrossJoinLists<T>(IEnumerable<List<T>> listofObjects)
{
var result = from obj in listofObjects.First()
select new List<T> {obj};
for (var i = 1; i < listofObjects.Count(); i++)
{
var iLocal = i;
result = from obj in result
from obj2 in listofObjects.ElementAt(iLocal)
select new List<T>(obj){ obj2 };
}
return result;
}
}
Here's a non-recursive, non-Linq solution. I can't help feeling like I could have less looping and calculate the positions with division and modulo, but can't quite wrap my head around that.
static void Main(string[] args)
{
//build test list
List<string[]> myList = new List<string[]>();
myList.Add(new string[0]);
myList.Add(new string[0]);
myList.Add(new string[0]);
myList[0] = new string[] { "1", "2", "3"};
myList[1] = new string[] { "4", "5" };
myList[2] = new string[] { "7", "8", "9" };
object[][] xProds = GetProducts(myList.ToArray());
foreach(object[] os in xProds)
{
foreach(object o in os)
{
Console.Write(o.ToString() + " ");
}
Console.WriteLine();
}
Console.ReadKey();
}
static object[][] GetProducts(object[][] jaggedArray){
int numLists = jaggedArray.Length;
int nProducts = 1;
foreach (object[] oArray in jaggedArray)
{
nProducts *= oArray.Length;
}
object[][] productAry = new object[nProducts][];//holds the results
int[] listIdxArray = new int[numLists];
listIdxArray.Initialize();
int listPtr = 0;//point to current list
for(int rowcounter = 0; rowcounter < nProducts; rowcounter++)
{
//create a result row
object[] prodRow = new object[numLists];
//get values for each column
for(int i=0;i<numLists;i++)
{
prodRow[i] = jaggedArray[i][listIdxArray[i]];
}
productAry[rowcounter] = prodRow;
//move the list pointer
//possible states
// 1) in a list, has room to move down
// 2) at bottom of list, can move to next list
// 3) at bottom of list, no more lists left
//in a list, can move down
if (listIdxArray[listPtr] < (jaggedArray[listPtr].Length - 1))
{
listIdxArray[listPtr]++;
}
else
{
//can move to next column?
//move the pointer over until we find a list, or run out of room
while (listPtr < numLists && listIdxArray[listPtr] >= (jaggedArray[listPtr].Length - 1))
{
listPtr++;
}
if (listPtr < listIdxArray.Length && listIdxArray[listPtr] < (jaggedArray[listPtr].Length - 1))
{
//zero out the previous stuff
for (int k = 0; k < listPtr; k++)
{
listIdxArray[k] = 0;
}
listIdxArray[listPtr]++;
listPtr = 0;
}
}
}
return productAry;
}
One of the problems I encountred when I was doing this for a very large amount of codes was that with the example brian was given I actually run out of memory. To solve this I used following code.
static void foo(string s, List<Array> x, int a)
{
if (a == x.Count)
{
// output here
Console.WriteLine(s);
}
else
{
foreach (object y in x[a])
{
foo(s + y.ToString(), x, a + 1);
}
}
}
static void Main(string[] args)
{
List<Array> a = new List<Array>();
a.Add(new string[0]);
a.Add(new string[0]);
a.Add(new string[0]);
a[0] = new string[] { "T", "Z" };
a[1] = new string[] { "N", "Z" };
a[2] = new string[] { "3", "2", "Z" };
foo("", a, 0);
Console.Read();
}
private static void GetP(List<List<string>> conditions, List<List<string>> combinations, List<string> conditionCombo, List<string> previousT, int selectCnt)
{
for (int i = 0; i < conditions.Count(); i++)
{
List<string> oneField = conditions[i];
for (int k = 0; k < oneField.Count(); k++)
{
List<string> t = new List<string>(conditionCombo);
t.AddRange(previousT);
t.Add(oneField[k]);
if (selectCnt == t.Count )
{
combinations.Add(t);
continue;
}
GetP(conditions.GetRange(i + 1, conditions.Count - 1 - i), combinations, conditionCombo, t, selectCnt);
}
}
}
List<List<string>> a = new List<List<string>>();
a.Add(new List<string> { "1", "5", "3", "9" });
a.Add(new List<string> { "2", "3" });
a.Add(new List<string> { "93" });
List<List<string>> result = new List<List<string>>();
GetP(a, result, new List<string>(), new List<string>(), a.Count);
Another recursive function.