ZOJ3531: [SDOI2014] 旅行

#include<bits/stdc++.h>
using namespace std;
const int N=1e5+10;
const int M=1e7+10;
int w[N],c[N],last[N*2],s[17],root[N];
int son[N],deep[N],dfn[N],top[N],fa[N][17];
int mx[M],sum[M],ls[M],rs[M];
int n,q,cnt,tim,tot;
struct orz{
    int v,next;}e[N*2];
void add(int x,int y)
{
    cnt++;
    e[cnt].v=y;
    e[cnt].next=last[x];
    last[x]=cnt;
}
void dfs1(int x)
{
    son[x]=1;
    for (int i=1;i<=16;i++)
    {
        if (s[i]<=deep[x]) fa[x][i]=fa[fa[x][i-1]][i-1];
        else break;
    }
    for (int i=last[x];i;i=e[i].next)
    {
        int v=e[i].v;
        if (v==fa[x][0]) continue;
        deep[v]=deep[x]+1;
        fa[v][0]=x;
        dfs1(v);
        son[x]+=son[v];
    }
}
void dfs2(int x,int chain)
{
    tim++;
    dfn[x]=tim;
    top[x]=chain;
    int k=0;
    for (int i=last[x];i;i=e[i].next)
    {
        if (deep[e[i].v]>deep[x] && son[e[i].v]>son[k])
            k=e[i].v;
    }
    if (k) dfs2(k,chain);
    for (int i=last[x];i;i=e[i].next)
    {
        if (deep[e[i].v]>deep[x] && e[i].v!=k)
            dfs2(e[i].v,e[i].v);
    }
}
int lca(int x,int y)
{
    if (deep[x]<deep[y]) swap(x,y);
    int t=deep[x]-deep[y];
    for (int i=0;i<=16;i++)
        if (s[i]&t) x=fa[x][i];
    for (int i=16;i>=0;i--)
        if (fa[x][i]!=fa[y][i]) x=fa[x][i],y=fa[y][i];
    if (x==y) return x;
    return fa[x][0];
}
//===========================================================
void PushUp(int s)
{
    mx[s]=max(mx[ls[s]],mx[rs[s]]);
    sum[s]=sum[ls[s]]+sum[rs[s]];
}
void change(int &s,int l,int r,int pos,int val)
{
    if (!s) s=++tot;
    if (l==r)
    {
        mx[s]=sum[s]=val;
        return ;
    }
    int mid=(l+r)>>1;
    if (pos<=mid) change(ls[s],l,mid,pos,val);
    else change(rs[s],mid+1,r,pos,val);
    PushUp(s);
}
int querysum(int s,int l,int r,int L,int R)
{
    if (!s) return 0;
    if (L<=l&&r<=R) return sum[s];
    int mid=(l+r)>>1;
    int ret=0;
    if (L<=mid) ret+=querysum(ls[s],l,mid,L,R);
    if (R>mid) ret+=querysum(rs[s],mid+1,r,L,R);
    return ret;
}
int querymx(int s,int l,int r,int L,int R)
{
    if (!s) return 0;
    if (L<=l&&r<=R) return mx[s];
    int mid=(l+r)>>1;
    int ret=0;
    if (L<=mid) ret=max(ret,querymx(ls[s],l,mid,L,R));
    if (R>mid) ret=max(ret,querymx(rs[s],mid+1,r,L,R));
    return ret;
}
//===========================================================
int solvesum(int c,int x,int y)
{
    int ret=0;
    while (top[x]!=top[y])  //因为在这题中y是x的祖先所以不用考虑x和y的深度关系
    {
        ret+=querysum(root[c],1,n,dfn[top[x]],dfn[x]);
        x=fa[top[x]][0];
    }
    ret+=querysum(root[c],1,n,dfn[y],dfn[x]);
    return ret;
}
int solvemx(int c,int x,int y)
{
    int mx=0;
    while (top[x]!=top[y])
    {
        mx=max(mx,querymx(root[c],1,n,dfn[top[x]],dfn[x]));
        x=fa[top[x]][0];
    }
    mx=max(mx,querymx(root[c],1,n,dfn[y],dfn[x]));
    return mx;
}
//===========================================================
void pre()
{
    s[0]=1;
    for (int i=1;i<=16;i++) s[i]=s[i-1]*2;
}
int main()
{
    pre();
    scanf("%d%d",&n,&q);
    for (int i=1;i<=n;i++)scanf("%d%d",&w[i],&c[i]);
    int x,y;
    for (int i=1;i<n;i++)
    {
        scanf("%d%d",&x,&y);
        add(x,y); add(y,x);
    }
    dfs1(1); dfs2(1,1);

    for (int i=1;i<=n;i++)
        change(root[c[i]],1,n,dfn[i],w[i]);

    char op[5];
    while (q--)
    {
        scanf("%s",op);
        scanf("%d%d",&x,&y);
        if (op[0]==‘C‘)
        {
            if (op[1]==‘C‘)
            {
                change(root[c[x]],1,n,dfn[x],0);
                c[x]=y;
                change(root[c[x]],1,n,dfn[x],w[x]);
            }
            else
            {
                change(root[c[x]],1,n,dfn[x],y);
                w[x]=y;
            }
        }
        else
        {
            int f=lca(x,y);
            if (op[1]==‘S‘)
            {
                int t=solvesum(c[x],x,f)+solvesum(c[x],y,f);g
                if (c[x]==c[f]) t-=w[f];
                printf("%d\n",t);
            }
            else
            {
                int t=max(solvemx(c[x],x,f),solvemx(c[x],y,f));
                printf("%d\n",t);
            }
        }
    }
    return 0;
}