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# suvojit-0x55aa/Det.java

Last active Jul 23, 2016
Determinant of a Matrix Laplace Method
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 import javax.naming.OperationNotSupportedException; import java.lang.Exception; import java.lang.Math; import java.lang.String; import java.lang.System; import java.util.Scanner; class Matrix { private int mat[][]; private int n,m; Matrix (int a[][]) { this.mat = (int[][])a.clone(); this.n = a.length; this.m = a[0].length; } public void print_mat () { print_mat(mat); } private void print_mat (int a[][]) { for (int i = 0; i < a.length; ++i) { for (int j = 0; j < a[0].length; ++j) System.out.print(a[i][j] + " "); System.out.print("\n"); } } public int determinant () { if (n == m) return determinant(mat,n); else return 0; } private int[][] cofactor (int a[][], int n, int p, int q) { int cofac[][] = new int [n-1][n-1]; int x = 0, y = 0; for (int i = 0; i < n; ++i) { for (int j = 0; j < n; ++j) if (i != p && j != q) { cofac[x][y] = a[i][j]; y++; } if (y > n-2) { ++x; y = 0; } } return cofac; } private int determinant (int a[][], int n) { if (n == 1) return a[0][0]; else { int res = 0; for (int i = 0; i < n; ++i) res += ((int)Math.pow(-1, i+0)) * a[i][0] * determinant(cofactor(a, n, i, 0), n-1); return res; } } } class RunApp { public static void main (String arg[]) { Scanner readIn = new Scanner(System.in); int n = readIn.nextInt(); int a[][] = new int[n][n]; for (int i = 0; i < n; ++i) for (int j = 0; j < n; ++j) a[i][j] = readIn.nextInt(); Matrix x = new Matrix(a); //x.print_mat(); System.out.println(x.determinant()); } }

### suvojit-0x55aa commented Jul 23, 2016

 //Input 3 4 5 6 8 5 6 4 5 1 //Output 100