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860. 染色法判定二分图
https://www.acwing.com/problem/content/submission/code_detail/36295038/
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AcWing/860/860.cpp
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59
AcWing/860/860.cpp
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#include <iostream>
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#include <algorithm>
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#include <iterator>
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#include <vector>
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using std::cin;
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using std::cout;
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const char endl = '\n';
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const int N = 1e5 + 5;
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int n, m;
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std::vector<int> g[N];
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int color[N];
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bool dfs(int u, int c) {
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color[u] = c;
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for (int v : g[u]) {
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if (~color[v]) { // 如果已经染色
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if (color[v] == c) return false; // 同色,矛盾
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} else {
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if (!dfs(v, c ^ 1)) return false;
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}
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}
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return true;
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}
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int main() {
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std::ios::sync_with_stdio(false);
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cin.tie(nullptr);
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std::fill(std::begin(color), std::end(color), -1);
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cin >> n >> m;
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for (int i = 1, u, v; i <= m; i++) {
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cin >> u >> v;
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g[u].push_back(v);
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g[v].push_back(u);
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}
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// 图可能不连通
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for (int i = 1; i <= n; i++) {
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if (!~color[i]) { // 如果没有染色
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if (!dfs(i, 0)) {
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cout << "No" << endl;
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exit(0);
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}
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}
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}
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cout << "Yes" << endl;
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return 0;
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}
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