自己yy的写法 可能有点奇怪吧 详情看代码 还是蛮短的

#include
      
       #include
       
        #include
        
         using namespace std;const int M=100055,inf=0x3f3f3f3f;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 t,root,sum,n,mn,delta,now,leave;int c[M][2],v[M],size[M],fa[M];void up(int k){size[k]=size[c[k][0]]+size[c[k][1]]+1;}void rotate(int x,int& k){    int y=fa[x],z=fa[y],l=0,r=1;    if(c[y][1]==x) l=1,r=0;    if(y==k) k=x;    else{
    if(c[z][0]==y) c[z][0]=x; else c[z][1]=x;}    fa[y]=x; fa[x]=z; fa[c[x][r]]=y;    c[y][l]=c[x][r]; c[x][r]=y;    up(y); up(x);}void splay(int x,int& k){    while(x!=k){        int y=fa[x],z=fa[y];        if(y!=k){            if(c[z][0]==y^c[y][0]==x) rotate(y,k);            else rotate(x,k);        }        rotate(x,k);    }}void insert(int &k,int w,int last){    if(!k){k=++sum; now=k; fa[k]=last; size[k]=1; v[k]=w; return ;}    if(w
         
          =rank) return find(l,rank);    else return find(r,rank-size[l]-1);}int main(){    n=read(); mn=read();    char ch[15]; int k,s;    while(n--){        scanf("%s",ch); k=read();        if(ch[0]=='I'&&k>=mn) insert(root,k-delta,0),splay(now,root);        if(ch[0]=='A') delta+=k;        if(ch[0]=='S') {            delta-=k,t=0,push_before(root,mn-delta); if(!t) continue;            splay(t,root); int l=c[t][0]; leave+=size[l]+1; root=c[t][1]; fa[root]=0;        }        if(ch[0]=='F'){            if(k>size[root]) printf("-1\n");            else s=find(root,size[root]-k+1),splay(s,root),printf("%d\n",v[root]+delta);        }        //printf("%d ",root); printf("%d [%d %d %d]\n",v[root],size[root],c[root][0],c[root][1]);    }    printf("%d\n",leave);    return 0;}