'commit'

TangDou/Topic/HuanGenDp/SubTree.cpp

@@ -0,0 +1,58 @@
+#include <bits/stdc++.h>
+using namespace std;
+#define int long long
+#define endl "\n"
+
+const int N = 100010, M = N << 1;
+int f[N], g[N], mod;
+int pro1[N], pro2[N];
+vector<int> edge[N];
+
+void dfs1(int u, int fa) {
+    f[u] = 1;
+    vector<int> edgeson;
+    for (int i = 0; i < edge[u].size(); i++) {
+        int v = edge[u][i];
+        if (v == fa) continue;
+        dfs1(v, u);
+        f[u] = 1LL * f[u] * (f[v] + 1) % mod;
+        edgeson.push_back(v); // 将子节点加入集合，方便之后操作
+    }
+    int pre1 = 1;
+    int pre2 = 1;
+
+    for (int i = 0; i < edgeson.size(); i++) {
+        pro1[edgeson[i]] = pre1;
+        pre1 = 1LL * pre1 * (f[edgeson[i]] + 1) % mod;
+    } // 预处理前缀积
+
+    for (int i = edgeson.size() - 1; i >= 0; i--) {
+        pro2[edgeson[i]] = pre2;
+        pre2 = 1LL * pre2 * (f[edgeson[i]] + 1) % mod;
+    } // 预处理后缀积
+}
+
+void dfs2(int u, int fa) {
+    if (fa == 0)
+        g[u] = 1; // 特判根节点
+    else
+        g[u] = (g[fa] * (1LL * pro1[u] * pro2[u] % mod) % mod + 1) % mod;
+    for (int i = 0; i < edge[u].size(); i++) {
+        if (edge[u][i] == fa) continue;
+        dfs2(edge[u][i], u);
+    }
+}
+signed main() {
+    int n;
+    cin >> n >> mod;
+
+    for (int i = 1; i < n; i++) {
+        int a, b;
+        cin >> a >> b;
+        edge[a].push_back(b);
+        edge[b].push_back(a);
+    }
+    dfs1(1, 0);
+    dfs2(1, 0);
+    for (int i = 1; i <= n; i++) printf("%d\n", 1LL * f[i] * g[i] % mod);
+}

TangDou/Topic/【换根DP】专题.md

@@ -1268,6 +1268,8 @@ signed main() {
     for (int i = 1; i <= n; i++) cout << g[i] - max(up[i], mx1[i]) << endl;
 }
 ```
+#### [$V-Subtree$](https://www.luogu.com.cn/problem/AT_dp_v)
+https://blog.csdn.net/Emm_Titan/article/details/123875298
 
 #### [$AcWing$ $1148$ 秘密的牛奶运输](https://www.cnblogs.com/littlehb/p/16054005.html)
 
@@ -1280,7 +1282,6 @@ https://www.cnblogs.com/DongPD/p/17498336.html
 
 #### [$P3647$ $APIO2014$ 连珠线](https://www.luogu.com.cn/problem/P3647)
 
-#### [$V-Subtree$](https://www.luogu.com.cn/problem/AT_dp_v)
+
-https://blog.csdn.net/Emm_Titan/article/details/123875298