题解 | 上三角矩阵判定

#include <stdio.h>

int main() {
    int a;
    int array[10][10];
    scanf("%d", &a);
    // Store the matrix into array
    for (int i = 0; i < a; i++) {
        for (int j = 0; j < a; j++) {
            scanf("%d", &array[i][j]);
        }
    }

    // Judge the member in matrix,
    // Row-0 judge 0 member from member[0][0]
    // Row-1 judge 1 member from member[1][0]
    // Row-X judge X member from member[X][0]
    for (int i = 0; i < a; i++) {
        for (int j = 0; j < i; j++) {
            if (array[i][j] != 0) {
                printf("NO");
                return 0;
            }
        }
    }
    printf("YES");
    return 0;
}