luogu1486 郁闷的出纳员

treap

#include <iostream>
#include <cstdlib>
#include <cstdio>
using namespace std;
int n, x, minn, delta=0, ans, rot=0, sze=0, val[100005], siz[100005], cnt[100005];
int l[100005], r[100005], rnd[100005];
char s[15];
void upd(int x){
    siz[x] = siz[l[x]] + siz[r[x]] + cnt[x];
}
void lRotate(int &k){
    int t=r[k]; r[k] = l[t]; l[t] = k;
    siz[t] = siz[k]; upd(k); k = t;
}
void rRotate(int &k){
    int t=l[k]; l[k] = r[t]; r[t] = k;
    siz[t] = siz[k]; upd(k); k = t;
}
void ins(int &k, int x){
    if(!k){
        k = ++sze; l[k] = r[k] = 0; val[k] = x;
        siz[k] = cnt[k] = 1; rnd[k] = rand();
        return ;
    }
    siz[k]++;
    if(val[k]==x)   cnt[k]++;
    else if(val[k]<x){
        ins(r[k], x);
        if(rnd[r[k]]<rnd[k])    lRotate(k);
    }
    else{
        ins(l[k], x);
        if(rnd[l[k]]<rnd[k])    rRotate(k);
    }
}
int del(int &k, int x){
    if(!k)  return 0;
    if(val[k]<x){
        int t=siz[l[k]]+cnt[k]; k = r[k];
        return t+del(k, x);
    }
    else{
        int t = del(l[k], x);
        siz[k] -= t;
        return t;
    }
}
int queryNum(int k, int x){
    if(!k)  return 0;
    if(siz[l[k]]>=x)    return queryNum(l[k], x);
    else if(x>siz[l[k]]+cnt[k]) return queryNum(r[k], x-siz[l[k]]-cnt[k]);
    else return val[k];
}
int main(){
    cin>>n>>minn;
    while(n--){
        scanf("%s %d", s, &x);
        if(s[0]==‘I‘){
            if(x>=minn)
                ins(rot, x-delta);
        }
        if(s[0]==‘A‘)   delta += x;
        if(s[0]==‘S‘){
            delta -= x;
            ans += del(rot, minn-delta);
        }
        if(s[0]==‘F‘){
            if(x>siz[rot])  printf("-1\n");
            else printf("%d\n", queryNum(rot, siz[rot]-x+1)+delta);
        }
    }
    printf("%d\n", ans);
    return 0;
}