题意转化

我们把它想象成一张图，给你的是a>b，我们就从b向a连一条边，最后的时候每次以i结点遍历整张图。看看能遍历到几个点就行了，最后的时候答案要-1.因为第i个点也算了一遍。

code

#include <bits/stdc++.h>
#define N 100010
#define M 2010

using namespace std;
int n, m, head[M], add_edge, vis[M], ans;
struct node {
    int next, to;
}edge[M];

int read() {
    int s = 0, f = 0; char ch = getchar();
    while (!isdigit(ch)) f |= (ch == '-'), ch = getchar();
    while (isdigit(ch)) s = s * 10 + (ch ^ 48), ch = getchar();
    return f ? -s : s;
}

void add(int from, int to) {
    edge[++add_edge].next = head[from];
    edge[add_edge].to = to;
    head[from] = add_edge;
}

void dfs(int x) {
    ans++; vis[x] = 1;
    for (int i = head[x]; i; i = edge[i].next) {
        int to = edge[i].to;
        if (vis[to]) continue;
        dfs(to);
    }
}

int main() {
    n = read(), m = read();
    for (int i = 1, x, y; i <= m; i++) {
        x = read(), y = read();
        add(y, x);
    }
    for (int i = 1; i <= n; i++) {
        memset(vis, 0, sizeof vis), ans = 0;
        dfs(i);
        cout << ans - 1<< "\n";
    }
    return 0;
}

​```