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257. 关押罪犯
https://www.acwing.com/problem/content/submission/code_detail/16205471/
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AcWing/257/257.cpp
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75
AcWing/257/257.cpp
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#include <iostream>
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#include <array>
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#include <utility>
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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 = 20005;
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int n, m;
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std::array<int, N> color;
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std::array<std::vector<std::pair<int, int>>, N> g;
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bool dfs(int u, int color, int limit) {
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::color[u] = color;
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for (auto e : g[u]) {
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int v = e.first,
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w = e.second;
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if (w <= limit) continue;
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if (::color[v]) {
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if (::color[v] == color) return false;
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} else if (!dfs(v, 3 - color, limit)) {
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return false;
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}
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}
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return true;
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}
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bool check(int limit) {
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std::fill(color.begin(), color.end(), 0);
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for (int i = 1; i <= n; i++) {
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if (!color[i]) {
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if (!dfs(i, 1, limit)) 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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cin >> n >> m;
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for (int i = 1, u, v, w; i <= m; i++) {
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cin >> u >> v >> w;
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g[u].emplace_back(v, w);
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g[v].emplace_back(u, w);
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}
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int l = 0, r = 1e9, ans = 0;
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while (l <= r) {
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int mid = (l + r) >> 1;
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if (check(mid)) {
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ans = mid;
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r = mid - 1;
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} else {
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l = mid + 1;
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}
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}
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cout << ans << endl;
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return 0;
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}
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