mirror of
https://git.sb/baoshuo/OI-codes.git
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94 lines
2.1 KiB
C++
94 lines
2.1 KiB
C++
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#include <iostream>
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#include <stack>
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#include <vector>
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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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int n, m, t, a, b;
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long long ans;
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std::vector<std::pair<int, int>> g[N], g2[N];
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// Tarjan
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int cnt, dfn[N], low[N];
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int scc_cnt, id[N], siz[N];
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std::stack<int> st;
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bool vis[N];
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void tarjan(int u) {
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dfn[u] = low[u] = ++cnt;
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st.push(u);
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vis[u] = true;
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for (auto e : g[u]) {
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int v = e.first;
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if (!dfn[v]) {
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tarjan(v);
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low[u] = std::min(low[u], low[v]);
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} else if (vis[v]) {
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low[u] = std::min(low[u], dfn[v]);
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}
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}
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if (low[u] == dfn[u]) {
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scc_cnt++;
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int v;
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do {
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v = st.top();
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st.pop();
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vis[v] = false;
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id[v] = scc_cnt;
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siz[scc_cnt]++;
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} while (v != u);
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}
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}
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// Longest Path
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int dist[N];
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int main() {
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cin >> n >> m;
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for (int i = 1; i <= n; i++) {
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g[0].push_back(std::make_pair(i, 1));
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}
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for (int i = 1; i <= m; i++) {
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cin >> t >> a >> b;
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if (t == 1) {
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g[a].push_back(std::make_pair(b, 0));
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g[b].push_back(std::make_pair(a, 0));
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} else if (t == 2) {
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g[a].push_back(std::make_pair(b, 1));
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} else if (t == 3) {
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g[b].push_back(std::make_pair(a, 0));
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} else if (t == 4) {
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g[b].push_back(std::make_pair(a, 1));
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} else {
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g[a].push_back(std::make_pair(b, 0));
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}
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}
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tarjan(0);
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for (int i = 0; i <= n; i++) {
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for (auto e : g[i]) {
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if (id[e.first] != id[i]) {
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g2[id[i]].push_back(std::make_pair(id[e.first], e.second));
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} else if (e.second) {
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cout << -1 << endl;
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exit(0);
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}
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}
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}
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for (int i = scc_cnt; i > 0; i--) {
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for (auto e : g2[i]) {
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int v = e.first,
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w = e.second;
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dist[v] = std::max(dist[v], dist[i] + w);
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}
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}
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for (int i = 1; i <= scc_cnt; i++) {
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ans += 1ll * dist[i] * siz[i];
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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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