bzoj1503: [NOI2004]郁闷的出纳员 fhqtreap版

#include<cstdio>
#include<cstring>
#include<algorithm>
using namespace std;
const int M=150000;
int read(){
    int ans=0,f=1,c=getchar();
    while(c<‘0‘||c>‘9‘){if(c==‘-‘) f=-1; c=getchar();}
    while(c>=‘0‘&&c<=‘9‘){ans=ans*10+(c-‘0‘); c=getchar();}
    return ans*f;
}
int n,m,sum,mn,leave,delta;
struct node{
    node *l,*r;
    int sz,v,rnd;
    void init(int w){sz=1; v=w; rnd=rand();}
    void up(){
        sz=1;
        if(l) sz+=l->sz;
        if(r) sz+=r->sz;
    }
    void split(node*&lw,node*&rw,int w){
        if(!this){lw=0; rw=0; return ;}
        if(w<=v){
            l->split(lw,l,w);
            rw=this;
        }
        else{
            r->split(r,rw,w);
            lw=this;
        }
        up();
    }
    int find(int rank){
        if(!this) return 0;
        int ls=l?l->sz:0;
        if(ls+1==rank) return v;
        else if(ls>=rank) return l->find(rank);
        else return r->find(rank-ls-1);
    }
    
}tr[M],*rt;
node* merge(node*a,node*b){
    if(!a) return b;
    if(!b) return a;
    if(a->rnd>b->rnd){
        a->r=merge(a->r,b);
        a->up();
        return a;
    }{
        b->l=merge(a,b->l);
        b->up();
        return b;
    }
}
int main()
{
    
    char ch[5];
    int w;
    n=read(); mn=read();
    while(n--){
        scanf("%s",ch); w=read();
        if(ch[0]==‘I‘&&w>=mn){
            tr[++sum].init(w-delta);
            node *p1,*p2;
            rt->split(p1,p2,w-delta);
            rt=merge(merge(p1,tr+sum),p2);
        }
        if(ch[0]==‘A‘) delta+=w;
        if(ch[0]==‘S‘){
            node *p;
            delta-=w; rt->split(p,rt,mn-delta); 
            if(p) leave+=p->sz;
        }
        if(ch[0]==‘F‘){
            if(!rt||w>rt->sz) { printf("-1\n"); continue;}
            printf("%d\n",rt->find(rt->sz-w+1)+delta);
        }
    }
    printf("%d\n",leave);
    return 0;
}