fork download
copy 
  1. using System;
  2. using System.CodeDom;
  3. using System.Collections.Generic;
  4. using System.Linq;
  5. using System.Text;
  6. using System.Threading.Tasks;
  7.  
  8. namespace ConsoleApplication4
  9. {
  10.     class Program
  11.     {
  12.         private static void Main(string[] args)
  13.         { var m = new int[,]
  14.             {
  15.                 {1, 2, 3, 4},
  16.                 {2, 1, 1, 1},
  17.                 {3, 1, 2, 1},
  18.                 {4, 1, 1, 1},
  19.             };
  20.  
  21.             Console.WriteLine(GetDeterminant(m));
  22.  
  23.             m = new int[,]
  24.             {
  25.                 {1, 2, 3, 4,5,1, 2, 3, 4,5,},
  26.                 {2, 1, 1, 1,3,1, 2, 3, 4,5,},
  27.                 {3, 1, 2, 1,8,1, 2, 3, 4,5,},
  28.                 {4, 1, 1, 1,1,1, 2, 3, 4,5,},
  29.                 {4, 10, 1, 2,1,1, 2, 3, 4,5,},
  30.                 {1, 2, 3, 4,5,1, 2, 3, 4,5,},
  31.                 {2, 1, 1, 1,3,1, 2, 3, 4,5,},
  32.                 {3, 1, 2, 1,8,1, 2, 3, 4,5,},
  33.                 {4, 1, 1, 1,1,1, 2, 3, 4,5,},
  34.                 {4, 10, 1, 2,1,1, 2, 3, 4,5,},
  35.             };
  36.  
  37.             Console.WriteLine(GetDeterminant(m));
  38.  
  39.  
  40.         }
  41.  
  42.  
  43.         private static void NextPermutation(int[] permutation, ref bool isPositive)
  44.         {
  45.             int lenght = permutation.Length, firstIndex = 0, secondIndex;
  46.  
  47.             for (int i = 0; i < lenght - 1; i++)
  48.                 if (permutation[i] < permutation[i + 1])
  49.                     firstIndex = i;
  50.  
  51.             secondIndex = lenght-1;
  52.  
  53.             while (permutation[firstIndex] > permutation[secondIndex])
  54.                 secondIndex--;
  55.  
  56.             swapInArray(permutation, firstIndex, secondIndex);
  57.             var count = (lenght - firstIndex-1) / 2;
  58.  
  59.             for (int i = 1; i <= count; i++)
  60.                 swapInArray(permutation, firstIndex + i, lenght - i);
  61.  
  62.             if (count%2 == 0) isPositive = !isPositive;
  63.         }
  64.  
  65.         private static void swapInArray(int[] array, int firstIndex, int secondIndex)
  66.         {
  67.             var temp = array[firstIndex];
  68.             array[firstIndex] = array[secondIndex];
  69.             array[secondIndex] = temp;
  70.         }
  71.  
  72.         static int GetDeterminant(int[,] matrix)
  73.         {
  74.             var rang = matrix.GetLength(0);
  75.             if(rang != matrix.GetLength(1)) // fatal error
  76.                 throw new Exception("Bad matrix");
  77.             if (rang == 1) return matrix[0, 0];
  78.  
  79.             var indexes = new int[rang];
  80.  
  81.             var countOfPermutation = 1;
  82.  
  83.             for (int i = 0; i < rang; i++)
  84.             {
  85.                 indexes[i] = i;
  86.                 countOfPermutation *= (i + 1);
  87.             }
  88.  
  89.             int determinant = 0, multiplication;
  90.             bool isPositive = true;
  91.  
  92.             for (int i = 0; i < countOfPermutation; i++)
  93.             {
  94.                 multiplication = 1;
  95.                 for (int j = 0; j < rang; j++)
  96.                     multiplication *= matrix[j, indexes[j]];
  97.  
  98.                 determinant += multiplication * (isPositive?1:-1);
  99.  
  100.                 NextPermutation(indexes,ref isPositive);
  101.             }
  102.  
  103.             return determinant;
  104.         }
  105.     }
  106. }
  107.  
Success #stdin #stdout 0.9s 23952KB
comments (?)
stdin
copy 
Standard input is empty
stdout
copy 
-4
0
https://ideone.com/UXsvAl
language:
C# (gmcs 5.20.1)
created:
10 years ago
visibility:
secret

Share or Embed source code

Discover > Sphere Engine API

The brand new service which powers Ideone!

Discover > IDE Widget

Widget for compiling and running the source code in a web browser!