discoQ2.c

#include <stdio.h>
#define MAX 100

int main() {
    int N;
    scanf("%d", &N);

    int mat[MAX][MAX];
    int indeg[MAX] = {0}, order[MAX], front = 0, rear = 0, queue[MAX];

    for (int i = 0; i < N; i++)
        for (int j = 0; j < N; j++) {
            scanf("%d", &mat[i][j]);
            if (mat[i][j]) indeg[j]++;
        }

    // enqueue all zero indegree nodes
    for (int i = 0; i < N; i++)
        if (indeg[i] == 0) queue[rear++] = i;

    int idx = 0;
    while (front < rear) {
        int u = queue[front++];
        order[idx++] = u;
        for (int v = 0; v < N; v++) {
            if (mat[u][v]) {
                indeg[v]--;
                if (indeg[v] == 0) queue[rear++] = v;
            }
        }
    }

    for (int i = 0; i < N; i++)
        printf("%d%c", order[i], i == N-1 ? '\n' : ' ');

    return 0;
}