C语言数组:输入一个矩阵(5*5)，求矩阵下三角形元素之和

输入一个矩阵(5*5)，求矩阵下三角形元素之和

#include <stdio.h>

int main()
{
    const int n = 5;
    int a[n][n];
    for (int i = 0; i < n; i++)
        for (int j = 0; j < n; j++)
            scanf("%d", &a[i][j]);
    int sum = 0;
    for (int i = 0; i < n; i++)
        for (int j = 0; j <= i; j++)
            sum += a[i][j];
    printf("%d", sum);
    return 0;
}