洛谷P3642 [APIO2016]烟火表演

传送门

题解

fy大佬好强……我根本看不懂……

 //minamoto
 #include<bits/stdc++.h>
 #define ll long long
 using namespace std;
 #define getc() (p1==p2&&(p2=(p1=buf)+fread(buf,1,1<<21,stdin),p1==p2)?EOF:*p1++)
 char buf[<<],*p1=buf,*p2=buf;
 inline int read(){
     #define num ch-'0'
     char ch;bool flag=;int res;
     while(!isdigit(ch=getc()))
     (ch=='-')&&(flag=true);
     for(res=num;isdigit(ch=getc());res=res*+num);
     (flag)&&(res=-res);
     #undef num
     return res;
 }
 const int N=6e5+;
 int n,m,tot,fa[N],w[N],d[N],rt[N],L[N],R[N],dis[N];ll v[N],sum;
 int merge(int x,int y){
     if(!x||!y) return x+y;
     if(v[x]<v[y]) swap(x,y);
     R[x]=merge(R[x],y);
     if(dis[L[x]]<dis[R[x]]) swap(L[x],R[x]);
     dis[x]=dis[R[x]]+;return x;
 }
 int pop(int x){return merge(L[x],R[x]);}
 int main(){
 //    freopen("testdata.in","r",stdin);
     n=read(),m=read();
     for(int i=;i<=n+m;++i)
     fa[i]=read(),w[i]=read(),sum+=w[i],++d[fa[i]];
     for(int i=n+m;i>=;--i){
         ll l=,r=;
         if(i<=n){
             while(--d[i]) rt[i]=pop(rt[i]);
             r=v[rt[i]],rt[i]=pop(rt[i]);
             l=v[rt[i]],rt[i]=pop(rt[i]);
         }
         v[++tot]=l+w[i],v[++tot]=r+w[i];
         rt[i]=merge(rt[i],merge(tot,tot-));
         rt[fa[i]]=merge(rt[fa[i]],rt[i]);
     }
     while(d[]--) rt[]=pop(rt[]);
     while(rt[]) sum-=v[rt[]],rt[]=pop(rt[]);
     printf("%lld\n",sum);
     return ;
 }