[BZOJ]1503: [NOI2004]郁闷的出纳员

SB平衡树

#include<cstdio>
#define MN 100000
#define L(x) c[x][0]
#define R(x) c[x][1]
#define rtf MN+1
#define rt L(rtf)
#define INF 0x7FFFFFFF
int fa[MN+5],c[MN+5][2],s[MN+5],p[MN+5],mk[MN+5],z[MN+5],tn;
inline void mark(int x,int ad){z[x]+=ad;mk[x]+=ad;}
inline void down(int x){if(mk[x])mark(L(x),mk[x]),mark(R(x),mk[x]),mk[x]=0;}
inline void up(int x){s[x]=s[L(x)]+s[R(x)]+1;}
inline int ran()
{
    static int x=23333;
    return x^=x<<13,x^=x>>17,x^=x<<5;
}
void rotate(int x)
{
    int f=fa[x],ff=fa[f],l=R(f)==x,r=l^1;
    fa[f]=x;fa[x]=ff;fa[c[x][r]]=f;
    c[ff][R(ff)==f]=x;c[f][l]=c[x][r];c[x][r]=f;
    up(f);up(x);
}
void ins(int f,int t,int x)
{
    while(c[f][t])++s[f=c[f][t]],down(f),t=x>z[f];
    fa[c[f][t]=++tn]=f;z[tn]=x;p[tn]=ran();s[tn]=1;
    while(p[tn]>p[fa[tn]])rotate(tn);
}
int find(int x,int k)
{
    while(down(x),k)
        if(k<=s[L(x)])x=L(x);
        else if(k-=s[L(x)]+1)x=R(x);
    return x;
}
void del(int x)
{
    fa[c[fa[x]][0]=R(x)]=fa[x];
    while(x=fa[x])up(x);
}
int main()
{
    int n,m,x,cnt=0;char t[MN+5];
    p[rtf]=INF;
    scanf("%d%d",&n,&m);
    while(n--)
    {
        scanf("%s%d",t,&x);
        if(t[0]=='I')if(x>=m)ins(rtf,0,x);
        if(t[0]=='A')mark(rt,x);
        if(t[0]=='S'){mark(rt,-x);while(rt&&z[x=find(rt,1)]<m)del(x),++cnt;}
        if(t[0]=='F')printf("%d
",x>s[rt]?-1:z[find(rt,s[rt]-x+1)]);
    }
    printf("%d",cnt);
}