F - Select Edges

https://atcoder.jp/contests/abc259/submissions/35168987

AtCoder/ABC259/F/F.cpp

@@ -0,0 +1,67 @@
+#include <iostream>
+#include <algorithm>
+#include <functional>
+#include <limits>
+#include <utility>
+#include <vector>
+
+using std::cin;
+using std::cout;
+const char endl = '\n';
+
+const int N = 3e5 + 5;
+
+int n, d[N];
+long long f[N][2];
+std::vector<std::pair<int, int>> g[N];
+
+void dfs(int u, int fa) {
+    std::vector<long long> weights;
+
+    for (auto e : g[u]) {
+        int v = e.first,
+            w = e.second;
+
+        if (v == fa) continue;
+
+        dfs(v, u);
+        weights.push_back(f[v][0] + w - f[v][1]);
+
+        f[u][0] += f[v][1];
+        f[u][1] += f[v][1];
+    }
+
+    std::sort(weights.begin(), weights.end(), std::greater<>());
+
+    for (int i = 0; i < weights.size(); i++) {
+        if (weights[i] <= 0) break;
+        if (i < d[u] - 1) f[u][0] += weights[i];
+        if (i < d[u]) f[u][1] += weights[i];
+    }
+
+    if (!d[u]) f[u][0] = std::numeric_limits<int>::min();
+}
+
+int main() {
+    std::ios::sync_with_stdio(false);
+    cin.tie(nullptr);
+
+    cin >> n;
+
+    for (int i = 1; i <= n; i++) {
+        cin >> d[i];
+    }
+
+    for (int i = 1, u, v, w; i < n; i++) {
+        cin >> u >> v >> w;
+
+        g[u].emplace_back(v, w);
+        g[v].emplace_back(u, w);
+    }
+
+    dfs(1, 0);
+
+    cout << f[1][1] << endl;
+
+    return 0;
+}