D - Fake Plastic Trees

https://codeforces.com/contest/1694/submission/160924995

Codeforces/1694/D/D.cpp

@@ -0,0 +1,63 @@
+#include <iostream>
+#include <cstring>
+#include <vector>
+
+using std::cin;
+using std::cout;
+const char endl = '\n';
+
+const int N = 2e5 + 5;
+
+int t, n, ans;
+long long f[N];
+std::vector<int> g[N];
+std::pair<int, int> p[N];
+
+void dfs(int u) {
+    for (int v : g[u]) {
+        dfs(v);
+
+        f[u] += f[v];
+    }
+
+    if (f[u] < p[u].first) {
+        ans++;
+        f[u] = p[u].second;
+    }
+
+    f[u] = std::min(f[u], (long long)p[u].second);
+}
+
+int main() {
+    std::ios::sync_with_stdio(false);
+    cin.tie(nullptr);
+
+    cin >> t;
+
+    while (t--) {
+        memset(f, 0x00, sizeof(f));
+        ans = 0;
+
+        cin >> n;
+
+        for (int i = 2, x; i <= n; i++) {
+            cin >> x;
+
+            g[x].push_back(i);
+        }
+
+        for (int i = 1; i <= n; i++) {
+            cin >> p[i].first >> p[i].second;
+        }
+
+        dfs(1);
+
+        for (int i = 1; i <= n; i++) {
+            g[i].clear();
+        }
+
+        cout << ans << endl;
+    }
+
+    return 0;
+}