Add Transpose Matrix in C# (#4879)

Author: pascalecu

archive/c/c-sharp/TransposeMatrix.cs

@@ -0,0 +1,68 @@
+using System;
+using System.Collections.Generic;
+using System.Linq;
+
+public static class Program
+{
+    private static void ShowUsage()
+    {
+        Console.Error.WriteLine("Usage: please enter the dimension of the matrix and the serialized matrix");
+        Environment.Exit(1);
+    }
+
+    private static List<int> ParseIntegerList(string input)
+    {
+        if (string.IsNullOrWhiteSpace(input))
+            ShowUsage();
+
+        var tokens = input
+            .Split(',', StringSplitOptions.RemoveEmptyEntries | StringSplitOptions.TrimEntries);
+
+        var numbers = new List<int>();
+        foreach (var token in tokens)
+        {
+            if (!int.TryParse(token, out int value))
+                ShowUsage();
+
+            numbers.Add(value);
+        }
+
+        return numbers;
+    }
+
+    static List<int> TransposeMatrix(int cols, int rows, List<int> input)
+    {
+        var result = new List<int>(new int[rows * cols]);
+
+        for (int i = 0; i < rows; ++i)
+        {
+            for (int j = 0; j < cols; ++j)
+            {
+                int index = j * rows + i;
+                result[index] = input[i * cols + j];
+            }
+        }
+
+        return result;
+    }
+
+    static int Main(string[] args)
+    {
+        if (args.Length != 3)
+            ShowUsage();
+
+        if (!int.TryParse(args[0], out var cols))
+            ShowUsage();
+
+        if (!int.TryParse(args[1], out var rows))
+            ShowUsage();
+
+        var numbers = ParseIntegerList(args[2]);
+        if (numbers.Count != cols * rows)
+            ShowUsage();
+
+        var transposed = TransposeMatrix(cols, rows, numbers);
+        Console.WriteLine(string.Join(", ", transposed));
+        return 0;
+    }
+}