【bzoj 1036】树的统计（树链剖分）

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#include<bits/stdc++.h>#define INF 2147483640#define max(x,y) (x>y?x:y)#define min(x,y) (x<y?x:y)using namespace std;int n;int dep[30005],v[30005],top[30005],tim;int siz[30005],son[30005],fa[30005],pos[30005];int head[30005],nex[60005],to[60005],tp;struct data{int L,R,sum,Max;}tree[30005<<2];inline void add(int x,int y){    nex[++tp]=head[x];    head[x]=tp;    to[tp]=y;}void dfs1(int x,int father){    siz[x]=1;    for(int i=head[x];i;i=nex[i]){        if(to[i]==father)   continue;        fa[to[i]]=x;dep[to[i]]=dep[x]+1;        dfs1(to[i],x);        siz[x]+=siz[to[i]];        if(siz[to[i]]>siz[son[x]])   son[x]=to[i];    }}void dfs2(int x,int tp){    top[x]=tp;pos[x]=++tim;    if(!son[x])     return;    dfs2(son[x],tp);    for(int i=head[x];i;i=nex[i]){        if(to[i]==fa[x] || to[i]==son[x])   continue;        dfs2(to[i],to[i]);    }}void buildtree(int num,int L,int R){    tree[num].L=L;    tree[num].R=R;    if(L==R){        tree[num].Max=-INF;        return;    }    int mid=L+R>>1;    buildtree(num<<1,L,mid);    buildtree(num<<1|1,mid+1,R);}void change(int num,int x,int y){    if(tree[num].L==tree[num].R){        tree[num].sum=tree[num].Max=y;        return;    }    int mid=tree[num].L+tree[num].R>>1;    if(x<=mid)change(num<<1,x,y);    if(x>mid) change(num<<1|1,x,y);    tree[num].sum=tree[num<<1].sum+tree[num<<1|1].sum;    tree[num].Max=max(tree[num<<1].Max,tree[num<<1|1].Max);}int querysum(int num,int x,int y){    if(x<=tree[num].L && tree[num].R<=y)  return tree[num].sum;    int mid=tree[num].L+tree[num].R>>1;    if(y<=mid) return querysum(num<<1,x,y);    if(x>mid)  return querysum(num<<1|1,x,y);    return querysum(num<<1,x,y)+querysum(num<<1|1,x,y);}inline int searchsum(int x,int y){    int re=0;    while(top[x]!=top[y]){        if(dep[top[x]]<dep[top[y]])  swap(x,y);        re+=querysum(1,pos[top[x]],pos[x]);        x=fa[top[x]];    }    if(pos[x]>pos[y])    swap(x,y);    re+=querysum(1,pos[x],pos[y]);    return re;}int querymax(int num,int x,int y){    if(x<=tree[num].L && tree[num].R<=y)  return tree[num].Max;    int mid=tree[num].L+tree[num].R>>1;    if(y<=mid) return querymax(num<<1,x,y);    if(x>mid)  return querymax(num<<1|1,x,y);    return max(querymax(num<<1,x,y),querymax(num<<1|1,x,y));}inline int searchmax(int x,int y){    int re=-INF;    while(top[x]!=top[y]){        if(dep[top[x]]<dep[top[y]])  swap(x,y);        re=max(re,querymax(1,pos[top[x]],pos[x]));        x=fa[top[x]];    }    if(pos[x]>pos[y])    swap(x,y);    re=max(re,querymax(1,pos[x],pos[y]));    return re;}int main(){    scanf("%d",&n);    for(int i=1;i<n;++i){        int x,y;        scanf("%d%d",&x,&y);        add(x,y);        add(y,x);    }    for(int i=1;i<=n;++i)    scanf("%d",&v[i]);    dfs1(1,1);dfs2(1,1);    buildtree(1,1,n);    for(int i=1;i<=n;++i)    change(1,pos[i],v[i]);    int q;    scanf("%d",&q);    for(int i=1;i<=q;++i){        char opt[10];        int x,y;        scanf("%s%d%d",opt,&x,&y);        if(opt[0]=='C'){            v[x]=y;            change(1,pos[x],y);        }        else if(opt[1]=='M')    printf("%d\n",searchmax(x,y));        else printf("%d\n",searchsum(x,y));    }    return 0;}