foj 2082 树链剖分 第2天

#include <iostream>
#include <cstdio>
#include <cstring>
#include <algorithm>
using namespace std;
#define LL int
#define lson id << 1
#define rson id << 1|1
const  LL M = 100008;
LL ti[M],top[M],siz[M],son[M],father[M],tp,idx,dep[M];
struct Linetree{
    LL sum,l,r,mark;
    LL mid(){
        return (l+r)/2;
    }
}node[M*4];
struct {
    LL head;
}H[M];
struct {
    LL v,next;
}E[M];
void add(LL u,LL v){
    E[tp].v = v;
    E[tp].next = H[u]. head;
    H[u].head = tp++;
}

void dfs_1(LL u,LL fa){

    son[u] = 0;siz[u] = 1;father[u] = fa; dep[u] = dep[fa] + 1;
    for(LL i=H[u].head;i!=-1;i=E[i].next){
        LL v = E[i].v; 
        if(v == fa)continue;
        dfs_1(v,u);
        siz[u] += siz[v];
        if(siz[v] > siz[son[u]])son[u] = v ;
    }
}
void dfs_2(LL u,LL fa){
    ti[u] = idx++;
    top[u] = fa;
    if(son[u])dfs_2(son[u],fa);
    for(LL i=H[u].head;i!=-1;i = E[i].next){
        LL v = E[i].v;
        if(v == father[u]||v == son[u]) continue;
        dfs_2(v,v);
    }

}
/* 线段树*/
void build_tree(LL id,LL l,LL r){
    node[id].l = l;
    node[id].r = r;
    node[id].sum = 0;
    if(l == r) return;
    LL mid = node[id].mid();
    build_tree(lson,l,mid);
    build_tree(rson,mid+1,r);
}
void push_up(LL id){
    node[id].sum = node[lson].sum   +   node[rson].sum;
}
void update(LL id,LL k,LL w){
    if(node[id].l == k&&node[id].r == k){
        node[id].sum = w;
        return;
    }
    LL mid = node[id].mid();
    if(k <=mid)update(lson,k,w);
    else update(rson,k,w);
    push_up(id);
}
LL query(LL id,LL l,LL r){
    if(node[id].l == l && node[id].r == r)
        return node[id].sum;
    LL mid = node[id].mid();
    if(r <=mid )return query(lson,l,r);
    else if(l > mid)return query(rson,l,r);
    else {
        return query(lson,l,mid) + query(rson,mid+1,r);
    }
}
LL e[M][4];
LL findmax(LL u,LL v){
    LL f1 = top[u];
    LL f2 = top[v];
    int sum = 0;
    while(f1 != f2){
        if(dep[f1] < dep[f2]){
            swap(f1,f2);swap(u,v);
        }
        sum += query(1,ti[f1],ti[u]);
         u = father[f1];f1 = top[u];
    }
    if(u == v) return sum;
    if(dep[u] > dep[v] ) swap(u,v);
    sum += query(1,ti[son[u]],ti[v]);
    return sum;
}
void init(){
    memset(E,-1,sizeof(E));
    memset(H,-1,sizeof(H));
    tp = 0;
    idx = 0;
    memset(son,0,sizeof(son));
}
int main(){
   //freopen("input.txt","r",stdin);
    LL n,m,u,v,w;
    while(~scanf("%d%d",&n,&m)){
            init();
        for(LL i=0;i<n-1;i++){
            scanf("%d%d%d",&e[i][0],&e[i][1],&e[i][2]);
            add(e[i][0],e[i][1]);
            add(e[i][1],e[i][0]);
        }
        dfs_1(1,1);
        dfs_2(1,1);
        build_tree(1,1,idx-1);
        for(LL i=0;i<n-1;i++){
            if(dep[e[i][0]] > dep[e[i][1]])
                swap(e[i][0],e[i][1]);
                update(1,ti[e[i][1]],e[i][2]);
        }
        while(m --){
            scanf("%d%d%d",&w,&u,&v);
            if(w)printf("%d\n",findmax(u,v));
            else update(1,ti[e[u-1][1]],v);
        }
    }
}