Accept: 875    Submit: 2839
Time Limit: 1000 mSec    Memory Limit : 32768 KB

Problem Description

Input

Output

Sample Input

Sample Output

Source

FOJ有奖月赛-2012年4月（校赛热身赛）

#include<iostream>
#include<cstdio>
#include<cstring>
#include<queue>
#include<set>
#include<map>
#include<vector>
#include<stack>
#include<cmath>
#include<string>
#include<algorithm>
using namespace std;
typedef long long ll;
const int sigma_size=26;
const int N=100+50;
const int MAXN=50000+50;
const int inf=0x3fffffff;
const double eps=1e-8;
const int mod=100000000+7;
#define L(x) (x<<1)
#define R(x) (x<<1|1)
#define PII pair<int, int>
#define mk(x,y) make_pair((x),(y))
int n,m,edge_cnt,cnt;
int head[MAXN],sz[MAXN],son[MAXN],fa[MAXN],top[MAXN],dep[MAXN],pos[MAXN];
struct Edge{int u,v,w,next;
}edge[MAXN<<1];
struct node{int l,r;ll sum;
}segtree[MAXN<<2];
void init(){edge_cnt=cnt=0;memset(head,-1,sizeof(head));
}
void addedge(int u,int v,int w){edge[edge_cnt].u=u; edge[edge_cnt].v=v;  edge[edge_cnt].w=w; edge[edge_cnt].next=head[u]; head[u]=edge_cnt++;
}
void dfs1(int u,int pre,int depth){sz[u]=1; son[u]=0; dep[u]=depth; fa[u]=pre;for(int i=head[u];i!=-1;i=edge[i].next){int v=edge[i].v;if(v == pre)continue;dfs1(v,u,depth+1);sz[u]+=sz[v];if(sz[son[u]]<sz[v])son[u]=v;}
}
void dfs2(int u,int tp){pos[u]=cnt++; top[u]=tp;if(son[u]!=0)dfs2(son[u],top[u]);for(int i=head[u];i!=-1;i=edge[i].next){int v=edge[i].v;if(v == fa[u] || v == son[u])continue;dfs2(v,v);}
}
void build(int rt,int l,int r){segtree[rt].l=l; segtree[rt].r=r; segtree[rt].sum=0;if(l == r)return ;int mid=(l+r)>>1;build(L(rt),l,mid); build(R(rt),mid+1,r);
}
void push_up(int rt){segtree[rt].sum=segtree[L(rt)].sum+segtree[R(rt)].sum;
}
void update(int rt,int p,int x){if(segtree[rt].l == segtree[rt].r){segtree[rt].sum=x;return ;}int mid=(segtree[rt].l+segtree[rt].r)>>1;if(p<=mid)update(L(rt),p,x);else update(R(rt),p,x);push_up(rt);
}
ll query(int rt,int l,int r){if(segtree[rt].l == l && segtree[rt].r == r)return segtree[rt].sum;int mid=(segtree[rt].l+segtree[rt].r)>>1;if(r<=mid)return query(L(rt),l,r);else if(l>mid)return query(R(rt),l,r);else return query(L(rt),l,mid)+query(R(rt),mid+1,r);
}
ll solve(int u,int v){ll ans=0;while(top[u]!=top[v]){if(dep[top[u]]<dep[top[v]])swap(u,v);ans+=query(1,pos[top[u]],pos[u]);u=fa[top[u]];}if(dep[u]>dep[v])swap(u,v);if(u!=v)ans+=query(1,pos[u]+1,pos[v]);return ans;
}
int main(){while(~scanf("%d%d",&n,&m)){init();for(int i=1;i<n;i++){int u,v,w;scanf("%d%d%d",&u,&v,&w);addedge(u,v,w); addedge(v,u,w);}dfs1(1,1,1); dfs2(1,1); build(1,1,n-1);for(int i=0;i<edge_cnt;i+=2){int u=edge[i].u,v=edge[i].v,w=edge[i].w;if(dep[u]<dep[v])swap(u,v);update(1,pos[u],w);}for(int i=0;i<m;i++){int id,u,v;scanf("%d",&id);if(id == 0){int x,w;scanf("%d%d",&x,&w);x=(x-1)*2;u=edge[x].u; v=edge[x].v;if(dep[u]<dep[v])swap(u,v);update(1,pos[u],w);}else{scanf("%d%d",&u,&v);printf("%lld\n",solve(u,v));}}}
}