【jzoj4846】【行走】【树链剖分】【线段树】

题目大意

解题思路

由于下取整不影响，用树链剖分维护边权积，超过最大值赋为最大值，用线段树单点修改区间查询。

code

#include<set>#include<cmath>#include<cstdio>#include<cstring>#include<iostream>#include<algorithm>#define LL long long#define LD double#define max(a,b) ((a>b)?a:b)#define min(a,b) ((a>b)?b:a)#define fo(i,j,k) for(int i=j;i<=k;i++)#define fd(i,j,k) for(int i=j;i>=k;i--)using namespace std;int const inf=2147483647;int const maxn=100000,maxy=1000000001;int n,q,gra,tim,u[maxn+10],v[maxn+10],begin[maxn+10],size[maxn+10],heavy[maxn+10],dep[maxn+10],fa[maxn+10],belong[maxn+10],dfn[maxn+10],to[maxn*2+10],next[maxn*2+10];LL len[maxn*2+10],t[maxn*5+10];void insert(int u,int v,LL w){    to[++gra]=v;    len[gra]=w;    next[gra]=begin[u];    begin[u]=gra;}void dfs(int now,int pre){    size[now]=1;    int mx=0;    for(int i=begin[now];i;i=next[i])        if(to[i]!=pre){            dep[to[i]]=dep[now]+1;            dfs(to[i],now);            fa[to[i]]=now;            size[now]+=size[to[i]];            if(size[to[i]]>mx){                mx=size[to[i]];                heavy[now]=to[i];            }        }}LL maxv=1000000001;void change(int pos,int l,int r,int p,LL v){    if(l==r){        t[pos]=v;        return;    }    int mid=(l+r)/2;    if(p<=mid)change(pos*2,l,mid,p,v);    else change(pos*2+1,mid+1,r,p,v);    double tmp=double(t[pos*2])*double(t[pos*2+1]);    if(tmp>maxv)t[pos]=maxv;    else t[pos]=t[pos*2]*t[pos*2+1];}void dfss(int now,int pre,int v){    dfn[now]=++tim;    change(1,1,n,dfn[now],v);    for(int i=begin[now];i;i=next[i])        if(to[i]==heavy[now]){            belong[to[i]]=belong[now];            dfss(to[i],now,len[i]);        }    for(int i=begin[now];i;i=next[i])        if((to[i]!=pre)&&(to[i]!=heavy[now])){            belong[to[i]]=to[i];            dfss(to[i],now,len[i]);        }}LL qury(int pos,int l,int r,int ll,int rr){    int mid=(l+r)/2;    if((l==ll)&&(r==rr))return t[pos];    else if(rr<=mid)return qury(pos*2,l,mid,ll,rr);    else if(mid<ll)return qury(pos*2+1,mid+1,r,ll,rr);    else{        LL tmp1=qury(pos*2,l,mid,ll,mid),tmp2=qury(pos*2+1,mid+1,r,mid+1,rr);        double tmp=double(tmp1)*double(tmp2);        if(tmp>maxv)return maxv;        else return tmp1*tmp2;    }}LL lc(int u,int v,LL ans){    for(;u!=v;){        if(belong[u]==belong[v]){            if(dep[u]>dep[v])swap(u,v);            LL tmp=qury(1,1,n,dfn[u]+1,dfn[v]);            ans=(ans/qury(1,1,n,dfn[u]+1,dfn[v]));            return ans;        }else{            if(dep[belong[u]]<dep[belong[v]])swap(u,v);            LL tmp=qury(1,1,n,dfn[belong[u]],dfn[u]);            ans=(ans/qury(1,1,n,dfn[belong[u]],dfn[u]));            if(!ans)return ans;            u=fa[belong[u]];        }    }    return ans;}int main(){    freopen("walk.in","r",stdin);    freopen("walk.out","w",stdout);    scanf("%d%d",&n,&q);    maxv=maxv*maxv;    fo(i,1,n-1){        LL c;scanf("%d%d%lld",&u[i],&v[i],&c);        insert(u[i],v[i],c);insert(v[i],u[i],c);    }    dep[1]=1;dfs(1,0);    belong[1]=1;dfss(1,0,1);    fo(i,1,q){        int type;scanf("%d",&type);        if(type==1){            int x,y;LL v;scanf("%d%d%lld",&x,&y,&v);            printf("%lld\n",lc(x,y,v));        }else{            int p;LL c;scanf("%d%lld",&p,&c);            if(fa[u[p]]==v[p])change(1,1,n,dfn[u[p]],c);            else change(1,1,n,dfn[v[p]],c);        }    }    return 0;}