已知,除了dp之外的部分没有任何问题。只要把dp单独拿出来重新建图拓扑排序之后再dp就AC了,但是如果不显示的建出缩点后的图,直接在tarjan的时候dp就连样例都过不了了,,
然而这种方法确实理论上是正确的,在其他的一些tarjan缩点+dp的题里成功实践过,求助大佬帮王看看我是不是哪里写的有问题 /jk
#include <bits/stdc++.h>
using namespace std;
const int N = 1e5 + 5;
#define pii pair<int, int>
#define ll long long
int n, k;
vector<pii> g[N], e[N];
int low[N], dfn[N], idx, ind[N], cnt, ins[N], bel[N];
int dp[N], ans, sz[N];
stack<int> stk;
vector<int> scc[N];
void dfs(int u) {
dfn[u] = low[u] = ++idx;
stk.push(u);
ins[u] = 1;
for (auto [v, w]: g[u])
if (!dfn[v]) {
dfs(v);
low[u] = min(low[u], low[v]);
} else if (ins[v]) low[u] = min(low[u], dfn[v]);
if (low[u] == dfn[u]) {
++cnt;
while (true) {
int v = stk.top(); stk.pop();
ins[v] = 0;
bel[v] = cnt;
scc[cnt].push_back(v);
for (auto [y, w]: g[v]) if (bel[y] && bel[y] != cnt) {
dp[cnt] = max(dp[cnt], dp[bel[y]] + w);
}
sz[cnt]++;
if (v == u) break;
}
}
}
int main() {
ios::sync_with_stdio(0), cin.tie(0);
cin >> n >> k;
for (int i = 1; i <= k; i++) {
int x, a, b; cin >> x >> a >> b;
if (x == 1) g[a].push_back({b, 0}), g[b].push_back({a, 0});
else if (x == 2) g[a].push_back({b, 1});
else if (x == 3) g[b].push_back({a, 0});
else if (x == 4) g[b].push_back({a, 1});
else if (x == 5) g[a].push_back({b, 0});
}
for (int i = 1; i <= n; i++) g[0].push_back({i, 1});
for (int i = 0; i <= n; i++) if (!dfn[i])
dfs(i);
ll ans = 0ll;
for (int i = 1; i <= cnt; i++) ans += (ll)dp[i] * sz[i];
cout << ans << endl;
return 0;
}