SPOJ 6779 Can you answer these queries VII 树链剖分

题目大意：给一颗树，树上每个节点都有一个权。两种操作，1 l r：询问l到r路径上所有点权组成的串的最大子串和；2 l r c：将l到r路径上的所有点权改为c。

思路：如果不是树，那么就基本和SPOJ 1043一样。但是题目是树，这里采用树链剖分。

//#pragma comment(linker, "/STACK:102400000,102400000")#include<cstdio>#include<cstring>#include<vector>#include<queue>#include<cmath>#include<cctype>#include<string>#include<algorithm>#include<iostream>#include<ctime>#include<map>#include<set>using namespace std;#define MP(x,y) make_pair((x),(y))#define PB(x) push_back(x)typedef long long LL;//typedef unsigned __int64 ULL;/* ****************** */const int INF=100011122;const double INFF=1e100;const double eps=1e-8;const LL mod=1000000007;const int NN=100010;const int MM=1000010;/* ****************** */struct TR{    int l,r,sum,fg;    bool ok;    int l_r,r_l,maxll;    int mid()    {        return (l+r)>>1;    }}tr[NN*4];int a[NN],b[NN];struct G{    int v,next;}E[NN*2];int p[NN],T;//c_dfs1int deep[NN],si[NN],per[NN],anc[NN];//c_dfs2int tsp,pos[NN],top[NN];void add(int u,int v){    E[T].v=v;    E[T].next=p[u];    p[u]=T++;}void c_dfs1(int u,int fa,int cen){    anc[u]=fa;    deep[u]=cen;    si[u]=1;    per[u]=-1;    int i,v;    for(i=p[u];i+1;i=E[i].next)    {        v=E[i].v;        if(v==fa)continue;        c_dfs1(v,u,cen+1);        si[u]+=si[v];        if(per[u]==-1 || si[v]>si[ per[u] ])            per[u]=v;    }}void c_dfs2(int u,int fa,int now_top){    pos[u]=++tsp;    top[u]=now_top;    if(per[u]!=-1)c_dfs2(per[u],u,now_top);    int i,v;    for(i=p[u];i+1;i=E[i].next)    {        v=E[i].v;        if(v==per[u] || v==fa)continue;        c_dfs2(v,u,v);    }}void up(TR &fa,TR &ls,TR &rs){    fa.sum=ls.sum+rs.sum;    fa.maxll=max(ls.maxll,rs.maxll);    fa.maxll=max(fa.maxll,ls.r_l+rs.l_r);    fa.l_r=max(ls.l_r,ls.sum+rs.l_r);    fa.r_l=max(rs.r_l,rs.sum+ls.r_l);}void push_up(int R){    up(tr[R],tr[R<<1],tr[R<<1|1]);}void down(int R,int col){    tr[R].fg=col;    tr[R].ok=true;    tr[R].sum=col*(tr[R].r-tr[R].l+1);    if(col>0)    {        tr[R].l_r=tr[R].r_l=tr[R].maxll=tr[R].sum;    }    else    {        tr[R].l_r=tr[R].r_l=tr[R].maxll=col;    }}void push_down(int R){    if(tr[R].ok)    {        down(R<<1,tr[R].fg);        down(R<<1|1,tr[R].fg);        tr[R].ok=false;    }}void build(int l,int r,int R){    tr[R].l=l;    tr[R].r=r;    tr[R].ok=false;    if(l==r)    {        tr[R].sum=tr[R].l_r=tr[R].r_l=tr[R].maxll=b[l];        return;    }    int mid=tr[R].mid();    build(l,mid,R<<1);    build(mid+1,r,R<<1|1);    push_up(R);}void update(int l,int r,int R,int col){    if(l<=tr[R].l && tr[R].r<=r)    {        down(R,col);        return;    }    push_down(R);    int mid=tr[R].mid();    if(l<=mid)        update(l,r,R<<1,col);    if(r>=mid+1)        update(l,r,R<<1|1,col);    push_up(R);}TR query(int l,int r,int R){    if(l<=tr[R].l && tr[R].r<=r)        return tr[R];    push_down(R);    int t=0,mid=tr[R].mid();    TR temp[3];    if(l<=mid)t++,temp[1]=query(l,r,R<<1);    if(r>=mid+1)t+=2,temp[2]=query(l,r,R<<1|1);    if(t<3)return temp[t];    up(temp[0],temp[1],temp[2]);    return temp[0];}void c_update(int u,int v,int col){    while(top[u]!=top[v])    {        if(deep[ top[u] ] > deep[ top[v] ])            swap(u,v);        update(pos[ top[v] ],pos[v],1,col);        v=anc[ top[v] ];    }    if(pos[u]>pos[v])        swap(u,v);    update(pos[u],pos[v],1,col);}int c_query(int u,int v){    int zz,yy,ans=0;    TR tt;    zz=yy=0;    while(top[u]!=top[v])    {        if(deep[ top[u] ] > deep[ top[v] ])        {           // printf("check==[%d,%d]\n",pos[ top[u] ],pos[u]);            tt=query(pos[ top[u] ],pos[u],1);           // printf("check ok\n");            ans=max(ans,tt.maxll);            ans=max(ans,zz+tt.r_l);            zz=max(zz+tt.sum,tt.l_r);            u=anc[ top[u] ];        }        else        {           // printf("check==[%d,%d]\n",pos[ top[v] ],pos[v]);            tt=query(pos[ top[v] ],pos[v],1);           // printf("check ok\n");            ans=max(ans,tt.maxll);            ans=max(ans,yy+tt.r_l);            yy=max(yy+tt.sum,tt.l_r);            v=anc[ top[v] ];        }    }    if(pos[u]>pos[v])    {        swap(u,v);        swap(zz,yy);    }    tt=query(pos[u],pos[v],1);    ans=max(ans,tt.maxll);    ans=max(ans,zz+tt.sum+yy);    ans=max(ans,zz+tt.l_r);    ans=max(ans,tt.r_l+yy);    return ans;}void solve(int n,int m){    int op,l,r,c;    build(1,n,1);    while(m--)    {        scanf("%d",&op);        if(op==1)        {            scanf("%d%d",&l,&r);            c=c_query(l,r);           // cout<<"ans==";            printf("%d\n",c);        }        else        {            scanf("%d%d%d",&l,&r,&c);            c_update(l,r,c);        }    }}int main(){    int n,m,i;    int u,v;    while(scanf("%d",&n)!=EOF)    {        for(i=1;i<=n;i++)            scanf("%d",&a[i]);        memset(p,-1,sizeof(p));        T=0;        for(i=1;i<n;i++)        {            scanf("%d%d",&u,&v);            add(u,v);            add(v,u);        }        c_dfs1(1,-1,0);        tsp=0;        c_dfs2(1,-1,1);        for(i=1;i<=n;i++)        {            b[ pos[i] ]=a[i];        }        scanf("%d",&m);        solve(n,m);    }    return 0;}