58 lines
1.2 KiB
C++
58 lines
1.2 KiB
C++
#include <bits/stdc++.h>
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using namespace std;
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const int N = 100010, M = N << 1;
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typedef pair<int, int> PII;
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int n, m;
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int color[N];
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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 x) {
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// 假设 1:黑，2：白，这样方便理解一些
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color[x] = 1;
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queue<PII> q;
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q.push({x, 1});
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while (q.size()) {
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PII t = q.front();
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q.pop();
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int u = t.first, c = t.second;
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for (int i = h[u]; ~i; i = ne[i]) {
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int v = e[i];
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if (!color[v]) {
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color[v] = 3 - c;
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q.push({v, 3 - c});
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} else if (color[v] == c) // 发现冲突
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return 0;
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}
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}
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return 1;
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}
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int main() {
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memset(h, -1, sizeof h);
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cin >> n >> m;
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int a, b;
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while (m--) {
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cin >> a >> b;
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add(a, b), add(b, a);
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}
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int flag = 1;
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for (int i = 1; i <= n; i++) {
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if (!color[i]) {
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if (!bfs(i)) {
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flag = 0;
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break;
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}
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}
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}
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if (flag)
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puts("Yes");
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else
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puts("No");
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return 0;
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} |