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H - Line Graph Matching
https://codeforces.com/gym/103427/submission/143971438
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Gym/103427/H/H.cpp
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68
Gym/103427/H/H.cpp
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#include <cstring>
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#include <iostream>
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using std::cin;
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using std::cout;
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using std::endl;
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const int N = 100005,
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M = 200005;
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int n, m, min;
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long long ans;
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// Graph
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int idx, head[N], edge[M << 1], ver[M << 1], next[M << 1];
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void add(int u, int v, int w) {
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next[idx] = head[u];
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ver[idx] = v;
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edge[idx] = w;
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head[u] = idx++;
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}
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// Tarjan
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int cnt, dfn[N], low[N];
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int siz[N];
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void tarjan(int u, int in_edge) {
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dfn[u] = low[u] = ++cnt;
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for (int i = head[u]; ~i; i = next[i]) {
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int v = ver[i];
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if (!dfn[v]) {
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tarjan(v, i);
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siz[u] += siz[v] + 1;
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low[u] = std::min(low[u], low[v]);
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if (low[v] > dfn[u]) {
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if (siz[v] % 2 == 0) {
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min = std::min(min, edge[i]);
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}
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} else {
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min = std::min(min, edge[i]);
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}
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} else if (i != (in_edge ^ 1)) {
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if (dfn[u] > dfn[v]) {
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siz[u]++;
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}
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low[u] = std::min(low[u], dfn[v]);
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min = std::min(min, edge[i]);
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}
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}
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}
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int main() {
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memset(head, 0xff, sizeof(head));
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cin >> n >> m;
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for (int i = 1; i <= m; i++) {
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int u, v, w;
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cin >> u >> v >> w;
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add(u, v, w);
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add(v, u, w);
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ans += w;
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}
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min = INT32_MAX;
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tarjan(1, 0);
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if (m & 1) ans -= min;
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cout << ans << endl;
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return 0;
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}
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