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| #include<iostream>
#include<cstdio>
#include<cmath>
#include<cstring>
#include<cstdlib>
#include<algorithm>
#include<ctime>
#include<iomanip>
#include<queue>
#include<stack>
#include<map>
#include<vector>
#define gh() getchar()
#define underMax(x,y) ((x)>(y)?(x):(y))
#define underMin(x,y) ((x)<(y)?(x):(y))
typedef long long ll;
using namespace std;
const int MAXN=1e5+1;
const int INF=0x7f7f7f7f;
template<class T>
inline void underRead(T &x)
{
x=0;
char ch=gh(),t=0;
while(ch<'0'||ch>'9') t|=ch=='-',ch=gh();
while(ch>='0'&&ch<='9') x=(x<<3)+(x<<1)+(ch^48),ch=gh();
if(t) x=-x;
}
int N,M,Idx,Vis[MAXN];
struct Splay
{
int chi[2],fa;
int size,val;
}Tree[MAXN];
int Root,Qx;
char op;
inline void underPushUp(int x)
{
Tree[x].size=Tree[Tree[x].chi[0]].size+Tree[Tree[x].chi[1]].size+1;
}
inline void underRotate(int x)
{
int y=Tree[x].fa,z=Tree[y].fa;
int k=Tree[y].chi[1]==x;
Tree[z].chi[Tree[z].chi[1]==y]=x;
Tree[x].fa=z;
Tree[y].chi[k]=Tree[x].chi[k^1];
Tree[Tree[x].chi[k^1]].fa=y;
Tree[x].chi[k^1]=y;
Tree[y].fa=x;
underPushUp(y);
underPushUp(x);
}
inline void Splay(int x,int k)
{
while(Tree[x].fa!=k)
{
int y=Tree[x].fa,z=Tree[y].fa;
if(z!=k)
if((Tree[y].chi[1]==x)^(Tree[z].chi[1]==y))
underRotate(x);
else
underRotate(y);
underRotate(x);
}
if(!k) Root=x;
}
inline void underInsert(int x)
{
int u=Root,p;
while(u)
{
p=u;
u=Tree[u].chi[x>Tree[u].val];
}
u=++Idx;
if(p) Tree[p].chi[x>Tree[p].val]=u;
Tree[u].val=x;
Tree[u].size=1;
Tree[u].fa=p;
Splay(u,0);
}
inline void underInit()
{
Root=++Idx;
Tree[Root].fa=0;
Tree[Root].val=0;
Tree[Root].size=1;
underInsert(N+1);
}
inline int underGetPre(int x)
{
int u=Root,res,v=Root;
while(u)
{
v=u;
if(Tree[u].val<x)
{
res=u;
u=Tree[u].chi[1];
}
else u=Tree[u].chi[0];
}
Splay(v,0);
return res;
}
inline int underGetNxt(int x)
{
int u=Root,res,v=Root;
while(u)
{
v=u;
if(Tree[u].val>x)
{
res=u;
u=Tree[u].chi[0];
}
else u=Tree[u].chi[1];
}
Splay(v,0);
return res;
}
inline void underErase(int x)
{
int l=underGetPre(x),r=underGetNxt(x);
Splay(l,0),Splay(r,l);
Tree[Tree[r].chi[0]].size=0;
Tree[Tree[r].chi[0]].fa=0;
Tree[r].chi[0]=0;
Splay(r,0);
}
int top,S[MAXN];
int main()
{
underRead(N),underRead(M);
underInit();
for(int i=1;i<=M;++i)
{
cin>>op;
if(op=='D')
{
underRead(Qx);
underInsert(Qx);
S[++top]=Qx;
Vis[Qx]=1;
}
else if(op=='R')
{
Vis[S[top]]=0;
underErase(S[top--]);
}
else if(op=='Q')
{
underRead(Qx);
if(Vis[Qx]) printf("0\n");
else printf("%d\n",Tree[underGetNxt(Qx)].val-Tree[underGetPre(Qx)].val-1);
}
}
return 0;
}
|