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OI-codes/Luogu/P3275/P3275.cpp
2022-01-04 21:33:02 +08:00

94 lines
2.1 KiB
C++

#include <iostream>
#include <stack>
#include <vector>
using std::cin;
using std::cout;
using std::endl;
const int N = 100005;
int n, m, t, a, b;
long long ans;
std::vector<std::pair<int, int>> g[N], g2[N];
// Tarjan
int cnt, dfn[N], low[N];
int scc_cnt, id[N], siz[N];
std::stack<int> st;
bool vis[N];
void tarjan(int u) {
dfn[u] = low[u] = ++cnt;
st.push(u);
vis[u] = true;
for (auto e : g[u]) {
int v = e.first;
if (!dfn[v]) {
tarjan(v);
low[u] = std::min(low[u], low[v]);
} else if (vis[v]) {
low[u] = std::min(low[u], dfn[v]);
}
}
if (low[u] == dfn[u]) {
scc_cnt++;
int v;
do {
v = st.top();
st.pop();
vis[v] = false;
id[v] = scc_cnt;
siz[scc_cnt]++;
} while (v != u);
}
}
// Longest Path
int dist[N];
int main() {
cin >> n >> m;
for (int i = 1; i <= n; i++) {
g[0].push_back(std::make_pair(i, 1));
}
for (int i = 1; i <= m; i++) {
cin >> t >> a >> b;
if (t == 1) {
g[a].push_back(std::make_pair(b, 0));
g[b].push_back(std::make_pair(a, 0));
} else if (t == 2) {
g[a].push_back(std::make_pair(b, 1));
} else if (t == 3) {
g[b].push_back(std::make_pair(a, 0));
} else if (t == 4) {
g[b].push_back(std::make_pair(a, 1));
} else {
g[a].push_back(std::make_pair(b, 0));
}
}
tarjan(0);
for (int i = 0; i <= n; i++) {
for (auto e : g[i]) {
if (id[e.first] != id[i]) {
g2[id[i]].push_back(std::make_pair(id[e.first], e.second));
} else if (e.second) {
cout << -1 << endl;
exit(0);
}
}
}
for (int i = scc_cnt; i > 0; i--) {
for (auto e : g2[i]) {
int v = e.first,
w = e.second;
dist[v] = std::max(dist[v], dist[i] + w);
}
}
for (int i = 1; i <= scc_cnt; i++) {
ans += 1ll * dist[i] * siz[i];
}
cout << ans << endl;
return 0;
}