atcoder/abc188E

Author: xirc

atcoder/abc188/E/main.cpp

@@ -0,0 +1,55 @@
+#include <bits/stdc++.h>
+
+using namespace std;
+using ll = int64_t;
+using ff = long double;
+
+int N, M;
+vector<int> A;
+vector<vector<int>> G;
+
+int ans;
+vector<bool> done;
+vector<int> maxi;
+void dfs(int v) {
+    if (done[v]) return;
+    done[v] = true;
+    maxi[v] = A[v];
+    for (int u : G[v]) {
+        dfs(u);
+        ans = max(ans, maxi[u] - A[v]);
+        maxi[v] = max(maxi[u], maxi[v]);
+    }
+}
+
+int solve() {
+    ans = numeric_limits<int>::lowest();
+    done.assign(N, 0);
+    maxi.assign(N, numeric_limits<int>::lowest());
+    for (int v = 0; v < N; ++v) {
+        if (done[v]) continue;
+        dfs(v);
+    }
+    return ans;
+}
+
+int main() {
+    ios_base::sync_with_stdio(false);
+    cin.tie(0); cout.tie(0);
+
+    cin >> N >> M;
+    A.assign(N, 0);
+    for (int i = 0; i < N; ++i) {
+        cin >> A[i];
+    }
+    G.assign(N, {});
+    for (int i = 0; i < M; ++i) {
+        int a, b;
+        cin >> a >> b;
+        --a, --b;
+        G[a].push_back(b);
+    }
+    cout << solve() << endl;
+
+    return 0;
+}