HDU 3966 RE 树链剖分 线段树 Aragorn's Story

题意：

给出一棵树，每个顶点上有一个权值。

操作：选择一条路径，并将路径上所有的点的权值同时加或减某个数。

查询：某个点的当前权值

分析：

树链剖分完毕后，就是简单的线段树区间更新。

提交的时候注意要要加一句扩栈的代码，用C++提交。

 #include <cstdio>
 #include <cstring>
 #include <algorithm>
 using namespace std;

 void read(int& x) {
     x = ;
     char c = ' ';
     while(c < '' || c > '') c = getchar();
     while('' <= c && c <= '') {
         x = x *  + c - '';
         c = getchar();
     }
 }

 const int maxn =  + ;
 const int maxnode = maxn * ;

 struct Edge
 {
     int v, nxt;
     Edge() {}
     Edge(int v, int nxt) :v(v), nxt(nxt) {}
 };

 int n, m, q;
 int a[maxn];

 int ecnt, head[maxn];
 Edge edges[maxn * ];

 void AddEdge(int u, int v) {
     edges[++ecnt] = Edge(v, head[u]);
     head[u] = ecnt;
     edges[++ecnt] = Edge(u, head[v]);
     head[v] = ecnt;
 }

 int dep[maxn], fa[maxn], son[maxn], sz[maxn];

 int tot, id[maxn], pos[maxn], top[maxn];

 void dfs(int u) {
     sz[u] = ; son[u] = -;
     for(int i = head[u]; i; i = edges[i].nxt) {
         int v = edges[i].v;
         if(v == fa[u]) continue;
         fa[v] = u;
         dep[v] = dep[u] + ;
         dfs(v);
         sz[u] += sz[v];
         if(son[u] == - || sz[v] > sz[son[u]]) son[u] = v;
     }
 }

 void dfs2(int u, int tp) {
     top[u] = tp;
     id[u] = ++tot;
     pos[tot] = u;
     if(son[u] == -) return;
     if(son[u]) dfs2(son[u], tp);
     for(int i = head[u]; i; i = edges[i].nxt) {
         int v = edges[i].v;
         if(v == fa[u] || v == son[u]) continue;
         dfs2(v, v);
     }
 }

 int sumv[maxnode], addv[maxnode];
 char cmd[];

 void pushup(int o) { sumv[o] = sumv[o<<] + sumv[o<<|]; }

 void build(int o, int L, int R) {
     if(L == R) { sumv[o] = a[pos[L]]; return; }
     int M = (L + R) / ;
     build(o<<, L, M);
     build(o<<|, M+, R);
     pushup(o);
 }

 void pushdown(int o, int L, int R) {
     if(addv[o]) {
         addv[o<<] += addv[o];
         addv[o<<|] += addv[o];
         int M = (L + R) / ;
         sumv[o<<] += (M - L + ) * addv[o];
         sumv[o<<|] += (R - M) * addv[o];
         addv[o] = ;
     }
 }

 void update(int o, int L, int R, int qL, int qR, int v) {
     if(qL <= L && R <= qR) {
         sumv[o] += (R - L + ) * v;
         addv[o] += v;
         return;
     }
     pushdown(o, L, R);
     int M = (L + R) / ;
     if(qL <= M) update(o<<, L, M, qL, qR, v);
     if(qR > M) update(o<<|, M+, R, qL, qR, v);
     pushup(o);
 }

 void UPDATE(int u, int v, int val) {
     int t1 = top[u], t2 = top[v];
     while(t1 != t2) {
         if(dep[t1] < dep[t2]) { swap(u, v); swap(t1, t2); }
         update(, , n, id[t1], id[u], val);
         u = fa[t1]; t1 = top[u];
     }
     if(dep[u] > dep[v]) swap(u, v);
     update(, , n, id[u], id[v], val);
 }

 int query(int o, int L, int R, int p) {
     if(L == R) return sumv[o];
     pushdown(o, L, R);
     int M = (L + R) / ;
     if(p <= M) return query(o<<, L, M, p);
     else return query(o<<|, M+, R, p);
 }

 int main()
 {
     while(scanf("%d%d%d", &n, &m, &q) == ) {
         for(int i = ; i <= n; i++) read(a[i]);

         memset(head, , sizeof(head));
         ecnt = ;
         for(int i = ; i < n; i++) {
             int u, v; read(u); read(v);
             AddEdge(u, v);
         }

         dfs();
         tot = ;
         dfs2(, );

         memset(addv, , sizeof(addv));
         build(, , n);

         while(q--) {
             scanf("%s", cmd);
             int u, v, d;
             read(u);
             if(cmd[] == 'Q') {
                 printf("%d\n", query(, , n, id[u]));
             } else {
                 read(v); read(d);
                 if(cmd[] == 'D') d = -d;
                 UPDATE(u, v, d);
             }
         }
     }

     return ;
 }

代码君