bzoj 1036: [ZJOI2008]树的统计Count （树链剖分）

ps：这道题过的人真多啊

一道树剖的模板题

（好像还可以用lct做， 然而我并不会

代码如下

 /**************************************************************
     Problem: 1036
     User: cminus
     Language: C++
     Result: Accepted
     Time:2380 ms
     Memory:4052 kb
 ****************************************************************/

 #include <cstdio>
 #include <vector>
 #include <algorithm>
 #include <cstring>
 using namespace std;
 const int N = ;
 #define ls (o << 1)
 #define rs (ls + 1)

 int n, w[N];
 int fa[N], size[N], hs[N], dep[N], top[N], pos[N], tot;
 int maxn[N*], sum[N*], L, R;
 vector < int > edge[N]; 

 inline void dfs1(int u, int d, int f){
     dep[u] = d; fa[u] = f; size[u] = ; hs[u] = -;
     int tmp = ;
     for (int i = ; i < edge[u].size(); i++){
         int &v = edge[u][i];
         if (v == f)  continue;
         dfs1(v, d + , u);
         if (size[v] > tmp)
             tmp = size[v], hs[u] = v;
         size[u] += size[v];
     }
 }

 inline void dfs2(int u, int t){
     top[u] = t, pos[u] = ++tot;
     if (hs[u] == -)    return ;
     dfs2(hs[u], t);
     for (int i = ; i < edge[u].size(); i++){
         int &v = edge[u][i];
         if (v != hs[u] && v != fa[u])
             dfs2(v, v);
     }
 }

 inline int getSum(int o, int l, int r){
     if (L <= l && r <= R) return sum[o];
     int mid = (l + r) >> , ans = ;
     if (L <= mid)    ans += getSum(ls, l, mid);
     if (R > mid)     ans += getSum(rs, mid + , r);
     return ans;
 }

 inline int getMax(int o, int l, int r){
     if (L <= l && r <= R) return maxn[o];
     int mid = l + r >> , ans = -0x3f3f3f3f;
     if (L <= mid)    ans = max(ans, getMax(ls, l, mid));
     if (R > mid) ans = max(ans, getMax(rs, mid + , r));
     return ans;
 }

 inline int getMax(int l, int r){
     L = l, R = r;
     return  getMax(, , tot);
 }

 inline int getSum(int l, int r){
     L = l, R = r;
     return getSum(, , tot);
 }

 inline void queryMax(int u, int v){
     int f1 = top[u], f2 = top[v], ans = -0x3f3f3f3f;
     while(f1 != f2){
         if (dep[f1] < dep[f2])
             swap(u, v), swap(f1, f2);
         ans = max(ans, getMax(pos[f1], pos[u]));
         u = fa[f1]; f1 = top[u];
     }
     if (dep[u] > dep[v]) swap(u, v);
     printf("%d\n", max(ans, getMax(pos[u], pos[v])));
 }

 inline void querySum(int u, int v){
     int f1 = top[u], f2 = top[v], ans = ;
     while(f1 != f2){
         if (dep[f1] < dep[f2])
             swap(u, v), swap(f1, f2);
         ans += getSum(pos[f1], pos[u]);
         u = fa[f1]; f1 = top[u];
     }
     if (dep[u] > dep[v]) swap(u, v);
     printf("%d\n", ans + getSum(pos[u], pos[v]));
 }

 inline void modify(int o, int l, int r, int u, int a){
     if(l == r){
         sum[o] = maxn[o] = a;
         return ;
     }
     int mid = l + r >> ;
     if (u <= mid)    modify(ls, l, mid, u, a);
     else    modify(rs, mid + , r, u, a);
     sum[o] = sum[ls] + sum[rs];
     maxn[o] = max(maxn[ls], maxn[rs]);
 }

 int main(){
     scanf("%d", &n);
     for (int i = ; i < n; i++){
         int x, y; scanf("%d %d", &x, &y);
         edge[x].push_back(y);
         edge[y].push_back(x);
     }
     for (int i = ; i <= n; i++) scanf("%d", &w[i]);
     dfs1(, , -); dfs2(, );
     for (int i = ; i <= n; i++)
         modify(, , tot, pos[i], w[i]);
     int q;  scanf("%d", &q);
     char str[]; int x, y;
     while(q--){
         scanf("%s%d%d", str, &x, &y);
         if (!strcmp(str, "QMAX"))   queryMax(x, y);
         else if (*str == 'C')   modify(, , tot, pos[x], y);
         else querySum(x, y);
     }
     return ;
 }