53 lines
1.1 KiB
C++
53 lines
1.1 KiB
C++
#include <bits/stdc++.h>
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using namespace std;
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typedef pair<int, int> PII;
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#define x first
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#define y second
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const int N = 1e5 + 10, M = N << 1;
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// 20个测试点，过了7个，得了35分,其它TLE
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// 邻接表
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int e[M], h[N], idx, ne[M];
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void add(int a, int b) {
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e[idx] = b, ne[idx] = h[a], h[a] = idx++;
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}
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bool bfs(int start, int dist) {
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queue<PII> q;
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q.push({start, dist});
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while (q.size()) {
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auto u = q.front();
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q.pop();
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if (u.x == 1 && u.y == 0) return true; // 在用完所有步数后，到达1号点，成功！
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for (int i = h[u.x]; ~i; i = ne[i]) {
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int v = e[i];
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if (u.y) q.push({v, u.y - 1});
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}
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}
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return false;
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}
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int main() {
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// 链式前向星
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memset(h, -1, sizeof h);
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int n, m, Q;
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cin >> n >> m >> Q;
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while (m--) {
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int a, b;
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cin >> a >> b;
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add(a, b), add(b, a); // 无向图，双向建边
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}
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while (Q--) {
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int u, dist;
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cin >> u >> dist;
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cout << (bfs(u, dist) ? "Yes" : "No") << endl;
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}
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return 0;
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} |