Bzoj 1036: [ZJOI2008]树的统计Count

题目链接：

http://www.lydsy.com/JudgeOnline/problem.php?id=1036

题解：

树链剖分＋线段树操作

代码：

#include <cmath>#include <cstdio>#include <cstring>#include <iostream>#include <algorithm>using namespace std;#define met(a,b) memset(a,b,sizeof(a))#define inf 0x7fffffffconst int maxn = 30005;struct EDGE{    int to,next;}Edge[maxn*2];struct Tree{    int left,right;    int sum,MAX;}tree[maxn<<2];int head[maxn];int cnt;void init1(){    cnt=0;    met(head,-1);}void Add_edge(int u,int v){    Edge[++cnt].to=v,Edge[cnt].next=head[u],head[u]=cnt;    Edge[++cnt].to=u,Edge[cnt].next=head[v],head[v]=cnt;}int size[maxn],fa[maxn],deep[maxn];void init2(){    met(size,0),met(fa,0),met(deep,0);}//size[i]:表示i这个节点下面的字节点的个数void Dfs1(int x){    size[x]=1;    for(int i=head[x];i!=-1;i=Edge[i].next)    {        if(Edge[i].to==fa[x])            continue;        deep[Edge[i].to]=deep[x]+1;        fa[Edge[i].to]=x;        Dfs1(Edge[i].to);        size[x]+=size[Edge[i].to];    }}int bl[maxn],pos[maxn];int sz;void init3(){    sz=0;    met(bl,0),met(pos,0);}//pos[i]:表示i这个节点在线段树的位置void Dfs2(int x,int chain){    int k=0;    sz++;    pos[x]=sz;//分配在线段树里的位置    bl[x]=chain;    for(int i=head[x];i!=-1;i=Edge[i].next)    {        if(deep[Edge[i].to]>deep[x]&&size[Edge[i].to]>size[k])            k=Edge[i].to;//选择子树中的最大的儿子来继承重链    }    if(k==0)        return;    Dfs2(k,chain);    for(int i=head[x];i!=-1;i=Edge[i].next)    {        if(deep[Edge[i].to]>deep[x]&&k!=Edge[i].to)            Dfs2(Edge[i].to,Edge[i].to);    }}//－－－－－－－线段树void build(int rt,int l,int r){    tree[rt].left=l;    tree[rt].right=r;    if(l==r)return;    int mid=(l+r)>>1;    build(rt<<1,l,mid);    build(rt<<1|1,mid+1,r);}void updata(int rt,int pos,int delta){    int left=tree[rt].left,right=tree[rt].right;    int mid=(left+right)>>1;    if(left==right)    {        tree[rt].sum=tree[rt].MAX=delta;        return;    }    if(pos<=mid)        updata(rt<<1,pos,delta);    else        updata(rt<<1|1,pos,delta);    tree[rt].sum=tree[rt<<1].sum+tree[rt<<1|1].sum;    tree[rt].MAX=max(tree[rt<<1].MAX,tree[rt<<1|1].MAX);}int querysum(int x,int y,int rt){    int left=tree[rt].left,right=tree[rt].right,mid=(left+right)>>1;    if(left==x&&right==y)        return tree[rt].sum;    if(y<=mid)        return querysum(x,y,rt<<1);    else if(x>mid)        return querysum(x,y,rt<<1|1);    else        return querysum(x,mid,rt<<1)+querysum(mid+1,y,rt<<1|1);}int querymax(int x,int y,int rt){    int left=tree[rt].left,right=tree[rt].right,mid=(left+right)>>1;    if(left==x&&right==y)        return tree[rt].MAX;    if(y<=mid)        return querymax(x,y,rt<<1);    else if(x>mid)        return querymax(x,y,rt<<1|1);    else        return max(querymax(x,mid,rt<<1),querymax(mid+1,y,rt<<1|1));}int slovemax(int x,int y){    int MAX=-inf;    while(bl[x]!=bl[y])    {        if(deep[bl[x]]<deep[bl[y]])            swap(x,y);        MAX=max(MAX,querymax(pos[bl[x]],pos[x],1));        x=fa[bl[x]];    }    if(pos[x]>pos[y])        swap(x,y);    MAX=max(MAX,querymax(pos[x],pos[y],1));    return MAX;}int slovesum(int x,int y){    int sum=0;    while(bl[x]!=bl[y])    {        if(deep[bl[x]]<deep[bl[y]])            swap(x,y);        sum+=querysum(pos[bl[x]],pos[x],1);        x=fa[bl[x]];    }    if(pos[x]>pos[y])        swap(x,y);    sum+=querysum(pos[x],pos[y],1);    return sum;}int room[maxn];int main(){    int n;    scanf("%d",&n);    init1(),init2(),init3();    for(int i=1;i<n;i++)    {        int x,y;        scanf("%d%d",&x,&y);        Add_edge(x,y);    }    met(room,0);    for(int i=1;i<=n;i++)        scanf("%d",&room[i]);    Dfs1(1);    Dfs2(1,1);    build(1,1,n);    for(int i=1;i<=n;i++)        updata(1,pos[i],room[i]);    int m;    scanf("%d",&m);    char s[maxn];    int x,y;    while(m--)    {        scanf("%s%d%d",s,&x,&y);        if(strcmp(s,"CHANGE")==0)            updata(1,pos[x],y);        else if(strcmp(s,"QMAX")==0)            printf("%d\n",slovemax(x,y));        else            printf("%d\n",slovesum(x,y));    }    return 0;}