P3806 【模板】点分治1

https://www.luogu.com.cn/record/76154506

Luogu/P3806/P3806.cpp

@@ -0,0 +1,128 @@
+#include <iostream>
+#include <limits>
+#include <queue>
+#include <vector>
+
+using std::cin;
+using std::cout;
+const char endl = '\n';
+
+const int N = 1e4 + 5,
+          K = 1e8 + 5;
+
+int n, m, query[N];
+int root, siz[N], max[N];
+int cnt, dist[N];
+bool vis[N], exists[K], ans[N];
+std::vector<std::pair<int, int>> g[N];
+
+void find(int u, int fa, int tot) {
+    siz[u] = 1;
+    max[u] = 0;
+
+    for (auto e : g[u]) {
+        int v = e.first,
+            w = e.second;
+
+        if (v == fa || vis[v]) continue;
+
+        find(v, u, tot);
+
+        siz[u] += siz[v];
+        max[u] = std::max(max[u], siz[v]);
+    }
+
+    max[u] = std::max(max[u], tot - siz[u]);
+
+    if (max[u] < max[root]) root = u;
+}
+
+void dis(int u, int fa, int sum) {
+    dist[++cnt] = sum;
+
+    for (auto e : g[u]) {
+        int v = e.first,
+            w = e.second;
+
+        if (v == fa || vis[v]) continue;
+
+        dis(v, u, sum + w);
+    }
+}
+
+void calc(int u) {
+    std::queue<int> q;
+
+    for (auto e : g[u]) {
+        int v = e.first,
+            w = e.second;
+
+        if (vis[v]) continue;
+
+        cnt = 0;
+        dis(v, u, w);
+
+        for (int i = 1; i <= cnt; i++) {
+            for (int j = 1; j <= m; j++) {
+                if (query[j] >= dist[i]) {
+                    ans[j] |= exists[query[j] - dist[i]];
+                }
+            }
+        }
+
+        for (int i = 1; i <= cnt; i++) {
+            q.push(dist[i]);
+            exists[dist[i]] = true;
+        }
+    }
+
+    while (!q.empty()) {
+        exists[q.front()] = false;
+        q.pop();
+    }
+}
+
+void solve(int u) {
+    vis[u] = true;
+    exists[0] = true;
+    calc(u);
+
+    for (auto e : g[u]) {
+        int v = e.first,
+            w = e.second;
+
+        if (vis[v]) continue;
+
+        max[root = 0] = std::numeric_limits<int>::max();
+        find(v, 0, siz[v]);
+        solve(root);
+    }
+}
+
+int main() {
+    std::ios::sync_with_stdio(false);
+
+    cin >> n >> m;
+
+    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));
+    }
+
+    for (int i = 1; i <= m; i++) {
+        cin >> query[i];
+    }
+
+    cnt = 0;
+    max[root = 0] = n;
+    find(1, 0, n);
+    solve(root);
+
+    for (int i = 1; i <= m; i++) {
+        cout << (ans[i] ? "AYE" : "NAY") << endl;
+    }
+
+    return 0;
+}