spoj 375 Query on a tree 链路剖分模板

在大神的看了下。，然后自己写了一下，对于链路剖分还是比较模式化的  边权型160++

#include<cstdio>#include<cstring>#include<iostream>#define M 20000#define lson (rt<<1)#define rson (rt<<1|1)#define inf 0x3f3f3f3fusing namespace std;struct G{    int head[M],en;    struct E{        int u,v,next,cost;    }e[M<<2];    void init(){        memset(head,-1,sizeof(head));en=0;    }    void add(int u,int v,int cost){        e[en].u=u;e[en].v=v;e[en].cost=cost;e[en].next=head[u];head[u]=en++;    }}g1;struct T{    struct E{        int l,r,tmax;    }e[M<<2];    int value[M];    void push_up(int rt){        e[rt].tmax=max(e[lson].tmax,e[rson].tmax);    }    void build(int l,int r,int rt){        e[rt].l=l;e[rt].r=r;e[rt].tmax=0;        if(l==r){            e[rt].tmax=value[l];            return ;        }        int mid=(l+r)>>1;        build(l,mid,lson);        build(mid+1,r,rson);        push_up(rt);    }    void update(int ul,int new_flag,int rt){        if(e[rt].l==ul&&e[rt].r==ul){            e[rt].tmax=new_flag;            return ;        }        int mid=(e[rt].l+e[rt].r)>>1;        if(ul<=mid) update(ul,new_flag,lson);        else update(ul,new_flag,rson);        push_up(rt);    }    int query(int ul,int ur,int rt){        if(ul<=e[rt].l&&ur>=e[rt].r){            return e[rt].tmax;        }        int mid=(e[rt].l+e[rt].r)>>1;        if(ur<=mid) return query(ul,ur,lson);        else if(ul>mid) return query(ul,ur,rson);        else{            int t1=query(ul,ur,lson);            int t2=query(ul,ur,rson);            return max(t1,t2);        }    }}tr;int my_que[M<<2],top[M],son[M],en,sz[M],fa[M],dep[M],hash[M],value[M];void build_tree(){    int l=0,r=-1;    my_que[++r]=1;    dep[1]=1;    sz[0]=0;    fa[1]=0;    while(l<=r){        int u=my_que[l++];son[u]=0;sz[u]=1;        for(int i=g1.head[u];i!=-1;i=g1.e[i].next){            int v=g1.e[i].v;            if(v==fa[u]) continue;            fa[v]=u;            value[v]=g1.e[i].cost;            dep[v]=dep[u]+1;            my_que[++r]=v;        }    }    for(int i=r;i>=0;i--){        int u=my_que[i];        for(int j=g1.head[u];j!=-1;j=g1.e[j].next){            int v=g1.e[j].v;            if(v==fa[u]) continue;            sz[u]+=sz[v];            if(sz[son[u]]<sz[v]) son[u]=v;        }    }    for(int i=0;i<=r;i++){        int u=my_que[i];        if(son[fa[u]]==u) top[u]=top[fa[u]];        else top[u]=u;    }}void re_build(int n){    en=1;    for(int i=1;i<=n;i++){        if(top[i]!=i) continue;        hash[i]=en;        tr.value[en++]=value[i];        for(int j=i;j;j=son[j]){            if(son[j]==0) continue;            hash[son[j]]=en;            tr.value[en++]=value[son[j]];        }    }    tr.build(1,en,1);}void work(int n){    build_tree();    re_build(n);}void change(int l,int new_flag){    int u=g1.e[(l<<1)-1].u;    int v=g1.e[(l<<1)-1].v;    if(dep[v]<dep[u]) swap(u,v);    tr.update(hash[v],new_flag,1);}int query(int x,int y){    int ans=-inf;    while(top[x]!=top[y]){        if(dep[top[x]]<dep[top[y]]) swap(x,y);        ans=max(ans,tr.query(hash[top[x]],hash[x],1));        x=fa[top[x]];    }    if(x==y) return ans;    if(dep[y]<dep[x]) swap(x,y);    ans=max(ans,tr.query(hash[son[x]],hash[y],1));    return ans;}int main(){    int cas;while(~scanf("%d",&cas)){        while(cas--){            int n;scanf("%d",&n);            g1.init();            for(int i=0;i<n-1;i++){                int u,v,cost;scanf("%d%d%d",&u,&v,&cost);                g1.add(u,v,cost);                g1.add(v,u,cost);            }            work(n);            char str[100];            while(1){                scanf("%s",str);                if(str[0]=='D') break;                if(str[0]=='C'){                    int t1,t2;scanf("%d%d",&t1,&t2);                    change(t1,t2);                }                if(str[0]=='Q'){                    int t1,t2;scanf("%d%d",&t1,&t2);                    int ans=query(t1,t2);                    printf("%d\n",ans);                }            }        }    }    return 0;}/*1141 2 91 3 71 4 12 5 132 6 106 11 116 12 123 7 84 8 64 9 24 10 59 13 313 14 4*/