POJ 2763 Housewife Wind (tree link splitting), poj2763

POJ 2763 Housewife Wind (tree link splitting), poj2763

Address: POJ 2763
Or tree link splitting template question... Not to mention ..
The Code is as follows:

#include <iostream>#include <string.h>#include <math.h>#include <queue>#include <algorithm>#include <stdlib.h>#include <map>#include <set>#include <stdio.h>using namespace std;#define LL long long#define pi acos(-1.0)#pragma comment(linker, "/STACK:1024000000,1024000000")const int mod=1e9+7;const int INF=0x3f3f3f3f;const double eqs=1e-3;const int MAXN=100000+10;#define root 1, n, 1#define lson l, mid, rt<<1#define rson mid+1, r, rt<<1|1int n, head[MAXN], cnt, tot;int dep[MAXN], fa[MAXN], son[MAXN], siz[MAXN], w[MAXN], top[MAXN];int sum[MAXN<<2];struct node{        int u, v, w, next;}edge[MAXN<<1];void add(int u, int v, int w){        edge[cnt].u=u;        edge[cnt].v=v;        edge[cnt].w=w;        edge[cnt].next=head[u];        head[u]=cnt++;}void init(){        memset(head,-1,sizeof(head));        cnt=0;        memset(dep,0,sizeof(dep));        memset(son,0,sizeof(son));        memset(sum,0,sizeof(sum));        tot=0;}void dfs1(int u, int p){        siz[u]=1;        for(int i=head[u];i!=-1;i=edge[i].next){                int v=edge[i].v;                if(v==p) continue ;                fa[v]=u;                dep[v]=dep[u]+1;                dfs1(v,u);                siz[u]+=siz[v];                if(siz[son[u]]<siz[v]) son[u]=v;        }}void dfs2(int u, int tp){        w[u]=++tot;top[u]=tp;        if(son[u]) dfs2(son[u],tp);        for(int i=head[u];i!=-1;i=edge[i].next){                int v=edge[i].v;                if(v!=son[u]&&v!=fa[u]){                        dfs2(v,v);                }        }}struct Line_Tree{        void PushUp(int rt)        {                sum[rt]=sum[rt<<1]+sum[rt<<1|1];        }        void Update(int p, int x, int l, int r, int rt)        {                if(l==r){                        sum[rt]=x;                        return ;                }                int mid=l+r>>1;                if(p<=mid) Update(p,x,lson);                else Update(p,x,rson);                PushUp(rt);        }        int Query(int ll, int rr, int l, int r, int rt)        {                if(ll<=l&&rr>=r){                        return sum[rt];                }                int mid=l+r>>1, ans=0;                if(ll<=mid) ans+=Query(ll,rr,lson);                if(rr>mid) ans+=Query(ll,rr,rson);                return ans;        }}lt;int solve(int u, int v){        int f1=top[u], f2=top[v], ans=0;        while(f1!=f2){                if(dep[f1]<dep[f2]){                        swap(u,v);                        swap(f1,f2);                }                ans+=lt.Query(w[f1],w[u],root);                u=fa[f1];f1=top[u];        }        if(u==v) return ans;        if(dep[u]<dep[v]){                swap(u,v);        }        return ans+lt.Query(w[son[v]],w[u],root);}int main(){        int q, s, u, v, c, i, x;        while(scanf("%d%d%d",&n,&q,&s)!=EOF){                init();                for(i=1;i<n;i++){                        scanf("%d%d%d",&u,&v,&c);                        add(u,v,c);                        add(v,u,c);                }                dfs1(1,-1);                dfs2(1,1);                for(i=0;i<cnt;i+=2){                        u=edge[i].u;                        v=edge[i].v;                        if(dep[u]<dep[v]) swap(u,v);                        lt.Update(w[u],edge[i].w,root);                }                while(q--){                        scanf("%d",&x);                        if(!x){                                scanf("%d",&v);                                printf("%d\n",solve(s,v));                                s=v;                        }                        else{                                scanf("%d%d",&x,&c);                                u=edge[x-1<<1].u;                                v=edge[x-1<<1].v;                                if(dep[u]<dep[v]) swap(u,v);                                lt.Update(w[u],c,root);                        }                }        }        return 0;}