BZOJ 4919: [Lydsy1706月赛]大根堆 启发式合并

#include<cstdio>
#include<iostream>
#include<set>
const int N=200010;
#define R register int
using namespace std;
inline int g() {
    R ret=0; register char ch; while(!isdigit(ch=getchar())); 
    do ret=ret*10+(ch^48); while(isdigit(ch=getchar())); return ret;
}
int n,m,cnt;
multiset<int>s[N];
int vr[N<<1],nxt[N<<1],fir[N],w[N];
inline void add(int u,int v) {vr[++cnt]=v,nxt[cnt]=fir[u],fir[u]=cnt;}
inline void dfs(int u) {
    for(R i=fir[u];i;i=nxt[i]) { R v=vr[i];
        dfs(v); if(s[u].size()<s[v].size()) swap(s[u],s[v]);
        for(multiset<int>::iterator it=s[v].begin();it!=s[v].end();++it) s[u].insert(*it);
    } multiset<int>::iterator it=s[u].lower_bound(w[u]); if(it!=s[u].end()) s[u].erase(it);
    s[u].insert(w[u]);
}
signed main() {
    n=g(); for(R i=1,fa;i<=n;++i) {
        w[i]=g(),fa=g(); if(i==1) continue; add(fa,i);
    } dfs(1); printf("%d\n",s[1].size()); 
}