determinant.cpp

#include <iostream>

int determinant(int** matrix,int n)
{
	int ans = 0;

	if(n == 2)
	{
		ans = matrix[0][0] * matrix[1][1] - matrix[0][1] * matrix[1][0];
		return ans;
	}

	for(int i = 0; i < n; i++)
	{
		int** array = new int*[n-1];
		for(int j = 0; j < n-1; j++)
		{
			array[j] = new int[n-1];
		}

		int x = 0, y = 0;
		for(int j = 1; j < n; j++)
		{
			x = 0;
			for(int k = 0; k < n; k++)
			{
				if(k == i) continue;
				array[y][x++] = matrix[j][k];
			}
			y++;
		}

		int sum = matrix[0][i] * determinant(array, n-1);
		if(i % 2) sum *= -1;
		ans += sum;

		for(int j = 0; j < n-1; j++)
			delete[] array[j];
		delete[] array;
	}

	return ans;
}

int main(void)
{
	using namespace std;

	int n;
	cin >> n;

	int** matrix = new int*[n];

	for(int i = 0; i < n; i++)
	{
		matrix[i] = new int[n];
	}

	for(int i = 0; i < n; i++)
		for(int j = 0; j < n; j++)
			cin >> matrix[i][j];

	cout << determinant(matrix, n) << endl;

	return 0;
}