✅ 选课 P2014

.gitignore

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+*.bin

pick-class/main.cc

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+#include <cstring>
+#include <iostream>
+using namespace std;
+
+const int MAXN = 300 + 5;
+
+typedef struct {
+  int left, right;
+  int score;
+} node;
+
+node tree[MAXN];
+int mem[MAXN][MAXN];
+int N, M;
+
+void insert(int current, int head) {
+  tree[current].right = tree[head].left;
+  tree[head].left = current;
+}
+
+int dfs(int node, int slots) {
+  if (node < 0 || !slots) {
+    return 0;
+  } else if (!node) { // Root node
+    return dfs(tree[node].left, slots);
+  }
+
+  if (mem[node][slots] > -1) {
+    return mem[node][slots];
+  }
+  mem[node][slots] = dfs(tree[node].right, slots); // When ignore this node
+  for (int i = 1; i <= slots; i++) {
+    int other = dfs(tree[node].left, i - 1) + dfs(tree[node].right, slots - i) +
+                tree[node].score;
+    mem[node][slots] = max(mem[node][slots], other);
+  }
+  return mem[node][slots];
+}
+
+int main() {
+  // Init
+  cin >> N >> M;
+  memset(tree, -1, sizeof tree);
+  memset(mem, -1, sizeof mem);
+  for (int i = 1; i <= N; i++) {
+    int depends, c;
+    cin >> depends >> c;
+    insert(i, depends);
+    tree[i].score = c;
+  }
+  // Calculating!
+  printf("%d", dfs(0, M));
+}

pick-class/main.in

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+7 4
+2 2
+0 1
+0 4
+2 1
+7 1
+7 6
+2 2