fy大佬好强……我根本看不懂……
1 //minamoto 2 #include<bits/stdc++.h> 3 #define ll long long 4 using namespace std; 5 #define getc() (p1==p2&&(p2=(p1=buf)+fread(buf,1,1<<21,stdin),p1==p2)?EOF:*p1++) 6 char buf[1<<21],*p1=buf,*p2=buf; 7 inline int read(){ 8 #define num ch-'0' 9 char ch;bool flag=0;int res; 10 while(!isdigit(ch=getc())) 11 (ch=='-')&&(flag=true); 12 for(res=num;isdigit(ch=getc());res=res*10+num); 13 (flag)&&(res=-res); 14 #undef num 15 return res; 16 } 17 const int N=6e5+5; 18 int n,m,tot,fa[N],w[N],d[N],rt[N],L[N],R[N],dis[N];ll v[N],sum; 19 int merge(int x,int y){ 20 if(!x||!y) return x+y; 21 if(v[x]<v[y]) swap(x,y); 22 R[x]=merge(R[x],y); 23 if(dis[L[x]]<dis[R[x]]) swap(L[x],R[x]); 24 dis[x]=dis[R[x]]+1;return x; 25 } 26 int pop(int x){return merge(L[x],R[x]);} 27 int main(){ 28 // freopen("testdata.in","r",stdin); 29 n=read(),m=read(); 30 for(int i=2;i<=n+m;++i) 31 fa[i]=read(),w[i]=read(),sum+=w[i],++d[fa[i]]; 32 for(int i=n+m;i>=2;--i){ 33 ll l=0,r=0; 34 if(i<=n){ 35 while(--d[i]) rt[i]=pop(rt[i]); 36 r=v[rt[i]],rt[i]=pop(rt[i]); 37 l=v[rt[i]],rt[i]=pop(rt[i]); 38 } 39 v[++tot]=l+w[i],v[++tot]=r+w[i]; 40 rt[i]=merge(rt[i],merge(tot,tot-1)); 41 rt[fa[i]]=merge(rt[fa[i]],rt[i]); 42 } 43 while(d[1]--) rt[1]=pop(rt[1]); 44 while(rt[1]) sum-=v[rt[1]],rt[1]=pop(rt[1]); 45 printf("%lld ",sum); 46 return 0; 47 }