// C++ program to find Determinant of a matrix
#include <bits/stdc++.h>
using namespace std;
// Dimension of input square matrix
#define N 4
// Function to get determinant of matrix
int determinantOfMatrix(int mat[N][N], int n)
{
int num1, num2, det = 1, index,
total = 1; // Initialize result
// temporary array for storing row
int temp[n + 1];
// loop for traversing the diagonal elements
for (int i = 0; i < n; i++)
{
index = i; // initialize the index
// finding the index which has non zero value
while (index < n && mat[index][i] == 0)
{
index++;
}
if (index == n) // if there is non zero element
{
// the determinant of matrix as zero
continue;
}
if (index != i)
{
// loop for swapping the diagonal element row and
// index row
for (int j = 0; j < n; j++)
{
swap(mat[index][j], mat[i][j]);
}
// determinant sign changes when we shift rows
// go through determinant properties
det = det * pow(-1, index - i);
}
// storing the values of diagonal row elements
for (int j = 0; j < n; j++)
{
temp[j] = mat[i][j];
}
// traversing every row below the diagonal element
for (int j = i + 1; j < n; j++)
{
num1 = temp[i]; // value of diagonal element
num2 = mat[j][i]; // value of next row element
// traversing every column of row
// and multiplying to every row
for (int k = 0; k < n; k++)
{
// multiplying to make the diagonal
// element and next row element equal
mat[j][k]
= (num1 * mat[j][k]) - (num2 * temp[k]);
}
total = total * num1; // Det(kA)=kDet(A);
}
}
// multiplying the diagonal elements to get determinant
for (int i = 0; i < n; i++)
{
det = det * mat[i][i];
}
return (det / total); // Det(kA)/k=Det(A);
}
// Driver code
int main()
{
/*int mat[N][N] = {{6, 1, 1},
{4, -2, 5},
{2, 8, 7}}; */
int mat[N][N] = { { 1, 0, 2, -1 },
{ 3, 0, 0, 5 },
{ 2, 1, 4, -3 },
{ 1, 0, 5, 0 } };
// Function call
printf("Determinant of the matrix is : %d",
determinantOfMatrix(mat, N));
return 0;
}
