[NOI2004]郁闷的出纳员

平衡树，裸题。
我们维护一下加法标记，然后剩下的就乱搞搞就好了。
这里使用了(splay)实现。

My Code:

#include <bits/stdc++.h>
#define il inline
const int maxn = 1e5 + 10;
const int inf = 0x3f3f3f3f;
using namespace std;
int n,m,i,j,k,root,add,tot,q,x,mn,padd,pnow;                
int fa[maxn],ch[maxn][2],val[maxn],size[maxn],cnt[maxn];                        
il void push_up(int o) {
    size[o] = size[ch[o][0]] + size[ch[o][1]] + cnt[o];
    return;
}      
il int which(int o) {
    return ch[fa[o]][1] == o;  
}      
il void clear(int o) {
    ch[o][0] = ch[o][1] = 0;    
    fa[o] = size[o] = cnt[o] = val[o] = 0;
    return;
}   
il void rotate(int o) {
    int f = fa[o],gf = fa[f],whi = which(o);         
    ch[f][whi] = ch[o][whi ^ 1];                
    fa[ch[f][whi]] = f;    
    ch[o][whi ^ 1] = f;                    
    fa[f] = o;fa[o] = gf;
    if(gf) ch[gf][ch[gf][1] == f] = o;        
    push_up(f);push_up(o);
    return;
}
il void splay(int o,int goal) {
    for(int f;(f = fa[o]) != goal;rotate(o)) {
        if(fa[f] != goal) rotate(which(f) == which(o) ? f : o);
    }
    if(!goal) root = o;  
    return;
}                                                            
il void insert(int v) {
    if(!root) {
        val[++tot] = v;cnt[tot] = 1;push_up(tot);                           
        root = 1;return;
    }
    int now = root,f = 0;
    while(1) {
        if(val[now] == v) {
            ++cnt[now];
            push_up(now);push_up(f);
            splay(now,0);return;      
        }
        f = now,now = ch[now][val[now] < v];      
        if(!now) {
            val[++tot] = v;cnt[tot] = 1;
            ch[f][val[f] < v] = tot;fa[tot] = f;             
            push_up(tot);push_up(f);          
            splay(tot,0);return;
        }
    }
}      
il int get_rank(int k) {
    int now = root,res = 0;
    while(1) {
        if(k < val[now]) {
            now = ch[now][0];
        } else {
            res += size[ch[now][0]];          
            if(k == val[now]) {splay(now,0);return res + 1;}        
            res += cnt[now];
            now = ch[now][1];
        }
    }
}                                
il int get_kth(int k) {
    int now = root;   
    while(1) {
        if(ch[now][0] && k <= size[ch[now][0]]) {
            now = ch[now][0];
        } else {
            k -= size[ch[now][0]] + cnt[now];if(k <= 0) return val[now];         
            now = ch[now][1];		
        }
    }
}
il int get_id(int k) {
    int now = root;
    while(1) {
        if(k < val[now]) {
            now = ch[now][0];
        } else {
            if(k == val[now]) return now; 
            now = ch[now][1];
        }
    }
}    
il int get_prev() {
    int now = ch[root][0];   
    while(ch[now][1]) now = ch[now][1];
    return now;
}
il int get_succ() {
    int now = ch[root][1];   
    while(ch[now][0]) now = ch[now][0];
    return now; 
}   
il void erase(int k) {
    get_rank(k);if(cnt[root] > 1) {--cnt[root];return;}    
    if(!ch[root][0] && !ch[root][1]) {
        clear(root);root = 0;return;
    } 
    if(!ch[root][0]) {
        int tmp = root;
        root = ch[root][1];                  
        fa[root] = 0;    
        clear(tmp);
        return;		
    }     
    if(!ch[root][1]) {
        int tmp = root;
        root = ch[root][0];
        fa[root] = 0;
        clear(tmp);
        return;
    } 
    int x = get_prev(),tmp = root;         
    splay(x,0);      
    ch[x][1] = ch[tmp][1];
    fa[ch[x][1]] = x;                  
    clear(tmp);      
    push_up(root);  
    return;       
}
int main() {
    scanf("%d %d",&q,&mn);      
    insert(-inf);insert(inf); 
    while(q--) {
        char opt[2];int x;scanf("%s%d",opt,&x);
        switch(opt[0]) {
            case 'I': if(x < mn) continue;insert(x - add);++padd;break; 
            case 'A': add += x;break;
            case 'S': {
                add -= x;
                insert(mn - add);                 
                int x = get_id(-inf),y = get_id(mn - add);    
                splay(x,0);splay(y,x);           
                int pos = ch[x][1];
                ch[pos][0] = 0;
                erase(mn - add);       
                break;
            }  
            case 'F': {
                pnow = get_rank(inf) - 2;if(pnow < x) {puts("-1");break;}   
                printf("%d
",get_kth(pnow + 2 - x) + add);
                break;
            }
        }
    }
    pnow = get_rank(inf) - 2;
    printf("%d
",padd - pnow);
    return 0;
}