请输入矩阵大小n: 9
100000000
020000000
003000000
000400000
000050000
000006000
000000700
000000080
000000009
int n, i, j;
cout << "请输入矩阵大小n: ";
cin >> n;

for (i = 0; i < n; i++){
    for (j = 0; j < n; j++){
        if (i == j){
            cout << i + 1;
            continue;
            cout << 0; // L1
        }
        // L2
    }
    printf("\n");
}