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50 lines
1.0 KiB
50 lines
1.0 KiB
#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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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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// u:点 c:颜色值
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bool dfs(int u, int c) {
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color[u] = c;
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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]) { // 没有染色过
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if (!dfs(v, 3 - c)) return 0; // 这个3-c用的太妙了
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} else if (color[v] == c)
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return 0; // 染色冲突
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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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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);
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}
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bool flag = 1;
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for (int i = 1; i <= n; i++)
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if (!color[i]) { // 把当前点染色为1
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if (!dfs(i, 1)) {
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flag = 0;
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break;
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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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} |