https://www.luogu.com.cn/problem/P6329

先建一顆點分樹
考慮樹上的每個節點維護什么
因為樹高是log的，所以怎么暴力怎么維護就好了

維護兩個前綴和，$u$的子樹的點距離$u$點的距離為$i$的個數
以及對于$fa[u]$的
然后一路往上跳，每次加上fa[u]的減去u的即可
相當于市點分治的減去重復計算的部分
空間處理用vector即可
code:

#include<bits/stdc++.h> #define N 500050 using namespace std; struct edge {int v, nxt; } e[N << 1]; int p[N], eid; void init() {memset(p, - 1, sizeof p);eid = 0; } void insert(int u, int v) {e[eid].v = v;e[eid].nxt = p[u];p[u] = eid ++; } int dep[N], fa[N][20]; int LCA(int x, int y) {if(dep[x] < dep[y]) swap(x, y);for(int i = 18; i >= 0; i --) if(dep[fa[x][i]] >= dep[y]) x = fa[x][i];if(x == y) return x;for(int i = 18; i >= 0; i --) if(fa[x][i] != fa[y][i]) x = fa[x][i], y = fa[y][i];return fa[x][0]; } int dis(int x, int y) {return dep[x] + dep[y] - 2 * dep[LCA(x, y)]; } void dfsp(int u) {dep[u] = dep[fa[u][0]] + 1;for(int i = p[u]; i + 1; i = e[i].nxt) {int v = e[i].v;if(v == fa[u][0]) continue;fa[v][0] = u; dfsp(v);} } vector<int> t[2][N]; int size[N], msize[N], vis[N], FA[N]; int sz, mx, rt; void dfs(int u, int ff) {size[u] = 1; msize[u] = 0;for(int i = p[u]; i + 1; i = e[i].nxt) {int v = e[i].v;if(v == ff || vis[v]) continue;dfs(v, u); size[u] += size[v];msize[u] = max(msize[u], size[v]);}msize[u] = max(msize[u], sz - size[u]);if(msize[u] < mx) mx = msize[u], rt = u; } void solve(int u, int ff, int n) {mx = sz = n, rt = 0;dfs(u, u); u = rt;FA[u] = ff; size[u] = sz;t[0][u].resize(sz + 5), t[1][u].resize(sz + 5);vis[u] = 1;for(int i = p[u]; i + 1; i = e[i].nxt) {int v = e[i].v;if(vis[v]) continue;solve(v, u, size[v]);} } #define lowbit(x) (x & -x) void update(int o, int u, int x, int y) { ++ x;for(; x <= size[u] + 1; x += lowbit(x)) t[o][u][x] += y; } int query(int o, int u, int x) { x = min(x + 1, size[u] + 1);int ret = 0;for(; x; x -= lowbit(x)) ret += t[o][u][x];return ret; } void Add(int x, int y) {for(int i = x; i; i = FA[i]) update(0, i, dis(i, x), y);for(int i = x; FA[i]; i = FA[i]) update(1, i, dis(FA[i], x), y); } int n, m, val[N]; int main() {init();scanf("%d%d", &n, &m);for(int i = 1; i <= n; i ++) scanf("%d", &val[i]);for(int i = 1; i < n; i ++) {int u, v;scanf("%d%d", &u, &v);insert(u, v), insert(v, u);}dfsp(1);for(int j = 1; j <= 18; j ++)for(int i = 1; i <= n; i ++) fa[i][j] = fa[fa[i][j - 1]][j - 1];solve(1, 0, n);for(int i = 1; i <= n; i ++) Add(i, val[i]);int lst = 0;while(m --) {int o, x, y;scanf("%d%d%d", &o, &x, &y);x ^= lst, y ^= lst;if(!o) {lst = query(0, x, y);for(int i = x; FA[i]; i = FA[i]) {int d = dis(x, FA[i]);if(d <= y) lst += query(0, FA[i], y - d) - query(1, i, y - d);} printf("%d\n", lst);} else Add(x, y - val[x]), val[x] = y;}return 0; }

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