C++交换二维数组两列位置

#include <iostream>
using namespace std;

int main(){
	int a[100][100],r,c,n,m;
	cin >> r >> c;
	for (int i = 0;i < r;i ++){
		for (int j = 0;j < c;j ++){
			cin >> a[i][j];
		}
	}
	cin >> n >> m;
	for (int i = 0;i < r;i ++){
		swap(a[i][n - 1],a[i][m - 1]);
	}
	for (int i = 0;i < r;i ++){
		for (int j = 0;j < c;j ++){
			cout << a[i][j] << " ";
		}
		cout << endl;
	}
	return 0;
}