luogu2869 [USACO07DEC]美食的食草动物Gourmet Grazers

#include <algorithm>
#include <iostream>
#include <cstdlib>
#include <cstdio>
using namespace std;
typedef long long ll;
int n, m, tmp, rot, cnt;
ll ans;
struct Cow{
    int pri, gre;
}cow[100005];
struct Gra{
    int pri, gre;
}gra[100005];
struct Treap{
    int val[100005], hav[100005], l[100005], r[100005], rnd[100005];
    void lRotate(int &k){
        int t=r[k]; r[k] = l[t]; l[t] = k; k = t;
    }
    void rRotate(int &k){
        int t=l[k]; l[k] = r[t]; r[t] = k; k = t;
    }
    void insert(int &k, int x){
        if(!k){
            k = ++cnt; hav[k] = 1;
            val[k] = x; rnd[k] = rand();
            return ;
        }
        if(val[k]==x)   hav[k]++;
        else if(val[k]<x){
            insert(r[k], x);
            if(rnd[r[k]]<rnd[k])    lRotate(k);
        }
        else{
            insert(l[k], x);
            if(rnd[l[k]]<rnd[k])    rRotate(k);
        }
    }
    void queryNxt(int k, int x){
        if(!k)  return ;
        if(val[k]>=x)   tmp = val[k], queryNxt(l[k], x);
        else    queryNxt(r[k], x);
    }
    void del(int &k, int x){
        if(!k)  return ;
        if(val[k]==x){
            if(hav[k]>1){
                hav[k]--;
                return ;
            }
            if(l[k]*r[k]==0)    k = l[k] + r[k];
            else if(rnd[l[k]]<rnd[r[k]])
                rRotate(k), del(k, x);
            else
                lRotate(k), del(k, x);
        }
        else if(val[k]<x)   del(r[k], x);
        else    del(l[k], x);
    }
}treap;
bool cmp1(Cow x, Cow y){
    return x.gre>y.gre;
}
bool cmp2(Gra x, Gra y){
    return x.gre>y.gre;
}
int main(){
    cin>>n>>m;
    for(int i=1; i<=n; i++)
        scanf("%d %d", &cow[i].pri, &cow[i].gre);
    for(int i=1; i<=m; i++)
        scanf("%d %d", &gra[i].pri, &gra[i].gre);
    sort(cow+1, cow+1+n, cmp1);
    sort(gra+1, gra+1+m, cmp2);
    int j=1;
    for(int i=1; i<=n; i++){
        tmp = -1;
        while(j<=m && gra[j].gre>=cow[i].gre){
            treap.insert(rot, gra[j].pri);
            j++;
        }
        treap.queryNxt(rot, cow[i].pri);
        if(tmp==-1){
            cout<<"-1"<<endl;
            return 0;
        }
        ans += tmp;
        treap.del(rot, tmp);
    }
    cout<<ans<<endl;
    return 0;
}