#533. 【2018年6月多校联训B组day6】追捕

https://sjzezoj.com/submission/16819

S2OJ/533/533.cpp

@@ -0,0 +1,51 @@
+#include <bits/stdc++.h>
+
+using namespace std;
+
+int n, m, opt, u, v, t, cnt;
+vector<int> g[1000005];
+bool vis[1000005];
+
+int gcd(int a, int b) {
+    if (b == 0) return a;
+    return gcd(b, a % b);
+}
+
+void bfs(int x) {
+    queue<int> q;
+    q.push(x);
+    vis[x] = true;
+    while (!q.empty()) {
+        int t = q.front();
+        q.pop();
+        for (auto i : g[t]) {
+            if (vis[i]) continue;
+            q.push(i);
+            vis[i] = true;
+        }
+    }
+}
+
+int main() {
+    std::ios::sync_with_stdio(false);
+    cin >> n >> m >> opt;
+    for (int i = 1; i <= m; i++) {
+        cin >> u >> v;
+        g[v].push_back(u);
+    }
+    cin >> t;
+    bfs(t);
+    for (int i = 1; i <= n; i++) {
+        cnt += vis[i];
+    }
+    cout << cnt / __gcd(cnt, n) << '/' << n / __gcd(cnt, n) << endl;
+    if (opt) {
+        for (int i = 1; i <= n; i++) {
+            if (vis[i]) {
+                cout << i << ' ';
+            }
+        }
+        cout << endl;
+    }
+    return 0;
+}