Merge pull request #1397 from AlgorithmWithGod/khj20006

[20251113] BOJ / P2 / ATM / 권혁준

Author: ShinHeeEul

khj20006/202511/13 BOJ P2 ATM.md

@@ -0,0 +1,94 @@
+```cpp
+#include <bits/stdc++.h>
+using namespace std;
+
+int N, M, S, P;
+vector<vector<int>> g(500001), r(500001), rv(500001);
+bitset<500001> rt;
+bitset<500001> rest;
+bitset<500001> vis;
+int m[500001]{}, c[500001]{}, mn[500001]{}, d[500001]{}, dp[500001]{};
+stack<int> st;
+set<pair<int, int>> ch;
+
+void dfs1(int n) {
+	for (int i : g[n]) if (!vis[i]) {
+		vis[i] = 1;
+		dfs1(i);
+	}
+	st.push(n);
+}
+
+int dfs2(int n, int t) {
+	c[n] = t;
+	int sum = m[n];
+	for (int i : r[n]) if (!vis[i]) {
+		vis[i] = 1;
+		sum += dfs2(i, t);
+	}
+	return sum;
+}
+
+void dfs3(int n) {
+	for (int i : rv[n]) {
+		d[i]++;
+		if (!vis[i]) {
+			vis[i] = 1;
+			dfs3(i);
+		}
+	}
+}
+
+int main() {
+	cin.tie(0)->sync_with_stdio(0);
+
+	cin >> N >> M;
+	for (int i = 0, a, b; i < M; i++) {
+		cin >> a >> b;
+		g[a].push_back(b);
+		r[b].push_back(a);
+	}
+	for (int i = 1; i <= N; i++) cin >> m[i];
+	cin >> S >> P;
+	for (int a; P--; rt[a] = 1) cin >> a;
+
+	for (int i = 1; i <= N; i++) if (!vis[i]) {
+		vis[i] = 1;
+		dfs1(i);
+	}
+	vis.reset();
+	int cnt = 0;
+	while (!st.empty()) {
+		int n = st.top(); st.pop();
+		if (vis[n]) continue;
+		cnt++;
+		vis[n] = 1;
+		mn[cnt] = dfs2(n, cnt);
+	}
+
+	for (int i = 1; i <= N; i++) {
+		for (int j : g[i]) if (c[i] != c[j] && !ch.count(make_pair(c[i], c[j]))) {
+			rv[c[i]].push_back(c[j]);
+			ch.emplace(c[i], c[j]);
+		}
+		if (rt[i]) rest[c[i]] = 1;
+	}
+
+	queue<int> q;
+	vis.reset();
+	dfs3(c[S]);
+	q.push(c[S]);
+	dp[c[S]] = mn[c[S]];
+	int ans = 0;
+	while (!q.empty()) {
+		int n = q.front(); q.pop();
+		if (rest[n]) ans = max(ans, dp[n]);
+		for (int i : rv[n]) {
+			dp[i] = max(dp[i], dp[n] + mn[i]);
+			if (!--d[i]) q.push(i);
+		}
+	}
+	cout << ans;
+
+}
+```