ZJOI2008 树的统计 树链剖分学习

水题，这次都没有给我傻逼的机会了，1A过了。直接上代码了

#include <iostream>
#include <cstdio>
#include <cstring>
#include <cmath>
#include <algorithm>
#define LL long long
#define INF 0x3fffffff
#define FOR(i,x,y)  for(int i = x;i < y;i ++)
#define IFOR(i,x,y) for(int i = x;i > y;i --)
#define lrt rt<<1
#define rrt rt<<1|1
#define lson rt<<1,l,mid
#define rson rt<<1|1,mid+1,r
#define MAXN 33000

using namespace std;

int n,p;

struct Edge{
    int u,v;
    int nt;
}edge[MAXN<<1];

int head[MAXN],edge_cnt;

void add_edge(int u,int v){
    edge[edge_cnt].u = u;
    edge[edge_cnt].v = v;
    edge[edge_cnt].nt = head[u];
    head[u] = edge_cnt++;
}

int val0[MAXN];
int fa[MAXN],sz[MAXN],son[MAXN],dep[MAXN],top[MAXN],w[MAXN],val[MAXN];
int totw;

void dfs1(int u,int father,int depth){
    fa[u] = father; dep[u] = depth; sz[u] = 1;
    int idd = -1,maxx = -1;
    for(int i = head[u];i != -1;i = edge[i].nt){
        int v = edge[i].v;
        if(v == father) continue;
        dfs1(v,u,depth+1);
        sz[u] += sz[v];
        if(maxx < sz[v])    {maxx = sz[v];idd = v;}
    }
    son[u] = idd;
}

void dfs2(int u,int father){
    if(son[u] == -1)    return;
    top[son[u]] = top[u];
    w[son[u]] = ++totw;
    val[totw] = val0[son[u]];
    dfs2(son[u],u);
    for(int i = head[u];i != -1;i = edge[i].nt){
        int v = edge[i].v;
        if(v == father) continue;
        if(v == son[u]) continue;
        top[v] = v;
        w[v] = ++totw;
        val[totw] = val0[v];
        dfs2(v,u);
    }
}

struct Tree{
    int l,r;
    int maxx,sum;
}tree[MAXN<<2];

void PushUp(int rt){
    tree[rt].maxx = max(tree[lrt].maxx,tree[rrt].maxx);
    tree[rt].sum = tree[lrt].sum + tree[rrt].sum;
}

void Build(int rt,int l,int r){
    tree[rt].l = l; tree[rt].r = r;
    if(l == r){
        tree[rt].maxx = tree[rt].sum = val[l];
        return;
    }
    int mid = (l+r)>>1;
    Build(lson);
    Build(rson);
    PushUp(rt);
}

void Modify(int rt,int x,int value){
    if(tree[rt].l == tree[rt].r){
        tree[rt].maxx = tree[rt].sum = value;
        return;
    }
    int mid = (tree[rt].l + tree[rt].r)>>1;
    if(x <= mid) Modify(lrt,x,value);
    else Modify(rrt,x,value);
    PushUp(rt);
}

int Q_Max(int rt,int l,int r){
    if(tree[rt].l == l && tree[rt].r == r){
        return tree[rt].maxx;
    }
    int mid = (tree[rt].l + tree[rt].r)>>1;
    if(r <= mid) return Q_Max(lrt,l,r);
    else if(l > mid) return Q_Max(rrt,l,r);
    else{
        return max(Q_Max(lson),Q_Max(rson));
    }
}

int Q_Sum(int rt,int l,int r){
    if(tree[rt].l == l && tree[rt].r == r){
        return tree[rt].sum;
    }
    int mid = (tree[rt].l + tree[rt].r)>>1;
    if(r <= mid) return Q_Sum(lrt,l,r);
    else if(l > mid) return Q_Sum(rrt,l,r);
    else{
        return Q_Sum(lson)+Q_Sum(rson);
    }
}

int Max(int l,int r){
    int ans = -INF;
    while(top[l] != top[r]){
        if(dep[top[l]] >= dep[top[r]]){
            ans = max(ans,Q_Max(1,w[top[l]],w[l]));
            l = fa[top[l]];
        }
        else{
            ans = max(ans,Q_Max(1,w[top[r]],w[r]));
            r = fa[top[r]];
        }
    }
    if(l == r)  ans = max(ans,Q_Max(1,w[l],w[r]));
    else if(dep[l] >= dep[r]){
        ans = max(ans,Q_Max(1,w[r],w[l]));
    }
    else ans = max(ans,Q_Max(1,w[l],w[r]));
    return ans;
}

int Sum(int l,int r){
    int ans = 0;
    while(top[l] != top[r]){
        if(dep[top[l]] >= dep[top[r]]){
            ans += Q_Sum(1,w[top[l]],w[l]);
            l = fa[top[l]];
        }
        else{
            ans += Q_Sum(1,w[top[r]],w[r]);
            r = fa[top[r]];
        }
    }
    if(l == r)  ans += Q_Sum(1,w[l],w[r]);
    else if(dep[l] >= dep[r]) ans += Q_Sum(1,w[r],w[l]);
    else ans += Q_Sum(1,w[l],w[r]);
    return ans;
}

int main()
{
    //freopen("test.in","r",stdin);
    while(~scanf("%d",&n)){
        edge_cnt = 0;
        memset(head,-1,sizeof(head));
        FOR(i,1,n){
            int u,v;
            scanf("%d%d",&u,&v);
            add_edge(u,v);
            add_edge(v,u);
        }
        FOR(i,1,n+1)    scanf("%d",&val0[i]);
        dfs1(1,-1,1);
        totw = 0;
        top[1] = 1;
        val[1] = val0[1];
        w[1] = ++totw;
        dfs2(1,-1);
        Build(1,1,totw);
        scanf("%d",&p);
        char op[10];
        while(p--){
            scanf("%s",op);
            if(!strcmp(op,"CHANGE")){
                int u,t;
                scanf("%d%d",&u,&t);
                Modify(1,w[u],t);
            }
            else if(!strcmp(op,"QMAX")){
                int l,r;
                scanf("%d%d",&l,&r);
                printf("%d
",Max(l,r));
            }
            else{
                int l,r;
                scanf("%d%d",&l,&r);
                printf("%d
",Sum(l,r));
            }
        }
    }
    return 0;
}

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