bzoj 1503 [NOI2004]郁闷的出纳员 splay tree

http://www.lydsy.com/JudgeOnline/problem.php?id=1503

#include <cstdio>
#include <cstring>
#include <iostream>
#include <algorithm>
using namespace std;
#define inf (1<<29)
const int maxn = 100010;
int sum , splaysz , tmp;
struct node {
    int p,chd[2],sz,mul,v;
    node (int P=0,int val=0) {
        chd[0]=chd[1]=0;sz=0;mul=1;
        p = P; v= val;
    }
}tree[maxn];
inline void sc(int y,int x,int p) { tree[y].chd[p]=x;tree[x].p=y; }
inline void update(int x) {
    tree[x].sz=tree[tree[x].chd[0]].sz+tree[tree[x].chd[1]].sz+tree[x].mul;
}
inline void rot(int x) {
    int y = tree[x].p;
    int w = tree[y].chd[1] == x;
    sc(tree[y].p,x,tree[tree[y].p].chd[1]==y);
    sc(y,tree[x].chd[w^1],w);
    sc(x,y,w^1);
    update(y);
    update(x);
}
void splay(int x,int rt) {
    while(tree[x].p!=rt) {
        int y = tree[x].p;
        int w = tree[y].chd[1]==x;
        if(tree[y].p != rt && tree[tree[y].p].chd[w]==y) rot(y);
        rot(x);
    }
}
void insert(int val) {
    if(tree[0].chd[0]==0) {
        tree[++splaysz] = node(0,val);
        tree[0].chd[0] = splaysz;
        update(splaysz);
        return;
    }
    int now = tree[0].chd[0];
    while(1) {
        if(val == tree[now].v) {
            tree[now].mul ++;
            update(now);
            splay(now,0);
            return;
        }
        int w = val > tree[now].v;
        if(tree[now].chd[w]) now = tree[now].chd[w];
        else {
            tree[++splaysz] = node(now,val);
            tree[now].chd[w]= splaysz;
            update(splaysz);
            splay(splaysz,0);
            return;
        }
    }
}
void find(int pos,int k) {
    if(tree[pos].sz < k) {
        puts("-1");
        return;
    }
    int x = tree[pos].chd[0];
    if(tree[x].sz>=k) find(x,k);
    else if(tree[x].sz+tree[pos].mul >= k) {
        printf("%d\n" , tree[pos].v-tmp);
    }
    else find(tree[pos].chd[1],k-tree[x].sz-tree[pos].mul);
}
void del() {
    int y = tree[0].chd[0];
    int x = tree[y].chd[1];
    sum += tree[y].sz - tree[x].sz - 1;
    tree[x].p = 0; tree[0].chd[0] = x;
}
int main() {
    int n , m ,x;
    char ch[11];
    while(cin >> n >> m) {
        sum = tmp = splaysz = 0;
        tree[0] = node(0 , inf);
        for(int i=0;i<n;i++) {
            scanf("%s%d",ch,&x);
            switch(ch[0]) {
                case 'I': if(x>=m) insert(x+tmp); break;
                case 'S': tmp += x; insert(m+tmp-1);del();break;
                case 'A': tmp -= x; break;
                case 'F':
                    if(tree[tree[0].chd[0]].sz < x) puts("-1");
                    else find(tree[0].chd[0],tree[tree[0].chd[0]].sz-x+1);
                    break;
            }
        }
        printf("%d\n" , sum);
    }
    return 0;
}