P4362 [NOI2002] 贪吃的九头龙

https://www.luogu.com.cn/record/77088166

Luogu/P4362/P4362.cpp

@@ -0,0 +1,72 @@
+#include <iostream>
+#include <algorithm>
+#include <array>
+#include <cstring>
+#include <vector>
+
+using std::cin;
+using std::cout;
+const char endl = '\n';
+
+const int N = 305;
+
+// f[子树根节点][多少个果子是被大头吃的][是否是大头吃掉了这个果子]
+int n, m, k, f[N][N][2], f2[N][2];
+std::vector<std::pair<int, int>> g[N];
+
+void dfs(int u, int fa) {
+    f[u][0][0] = f[u][1][1] = 0;
+
+    for (auto e : g[u]) {
+        int v = e.first,
+            w = e.second;
+
+        if (v == fa) continue;
+        dfs(v, u);
+
+        memcpy(f2, f[u], sizeof(f[u]));
+        memset(f[u], 0x3f, sizeof(f[u]));
+
+        for (int i = 0; i <= k; i++) {
+            for (int j = 0; j <= i; j++) {
+                f[u][i][0] = std::min(f[u][i][0], f2[i - j][0] + f[v][j][1]);
+
+                if (m == 2) {
+                    f[u][i][0] = std::min(f[u][i][0], f2[i - j][0] + f[v][j][0] + w);
+                } else {
+                    f[u][i][0] = std::min(f[u][i][0], f2[i - j][0] + f[v][j][0]);
+                }
+
+                f[u][i][1] = std::min({f[u][i][1], f2[i - j][1] + f[v][j][1] + w, f2[i - j][1] + f[v][j][0]});
+            }
+        }
+    }
+}
+
+int main() {
+    std::ios::sync_with_stdio(false);
+    cin.tie(nullptr);
+
+    cin >> n >> m >> k;
+
+    if (n - k < m - 1) {
+        cout << -1 << endl;
+
+        exit(0);
+    }
+
+    for (int i = 1, u, v, w; i < n; i++) {
+        cin >> u >> v >> w;
+
+        g[u].push_back(std::make_pair(v, w));
+        g[v].push_back(std::make_pair(u, w));
+    }
+
+    memset(f, 0x3f, sizeof(f));
+
+    dfs(1, 0);
+
+    cout << f[1][k][1] << endl;
+
+    return 0;
+}