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| #include <bits/stdc++.h>
using namespace std;
typedef long long ll;
#define endl '\n'
#define Turnoff std::ios::sync_with_stdio(false)
const int Max=2e5+5;
const int Mod=998244353;
const int inf=0x3f3f3f3f;
#define __DEBUG__
#ifdef __DEBUG__
#define DeBug(format, ...) \
{ \
fprintf(stdout, "\[%s:%d] \" format " ", \
__FUNCTION__ , __LINE__, ##__VA_ARGS__); \
}
#else
#define DeBug(format,...)
#endif
/*
*/
class SegTree{
public:
#define mid ((L+R)>>1)
#define Leftson now<<1
#define Rightson now<<1|1
struct segtree{int L,R,pos;};
segtree tree[Max<<2];
void push_up(int now){
tree[now].pos=min(tree[Leftson].pos,tree[Rightson].pos);
return;
}
void build(int L,int R,int now=1){
tree[now]={L,R,0};
//cout<<L<<" "<<R<<endl;
if(L==R)return;
//int mid=(L+R)>>1;
build(L,mid,Leftson);
build(mid+1,R,Rightson);
push_up(now);
return;
}
void updata(int qL,int qR,int val,int now=1){
if(qL<=tree[now].L&&qR>=tree[now].R){
tree[now].pos=val;
return;
}
if(qL<=tree[Leftson].R)updata(qL,qR,val,Leftson);
if(qR>=tree[Rightson].L)updata(qL,qR,val,Rightson);
push_up(now);return;
}
int query(int qL,int qR,int now=1){
if(qL>qR)return inf;
if(tree[now].R<=qR&&tree[now].L>=qL)return tree[now].pos;
int minnpos=inf;
if(tree[Leftson].R>=qL)minnpos=min(minnpos,query(qL,qR,Leftson));
if(tree[Rightson].L<=qR)minnpos=min(minnpos,query(qL,qR,Rightson));
push_up(now);
return minnpos;
}
}Val;
bool vis[Max];
int arr[Max],last[Max];
int main(){
//Turnoff;
int n;cin>>n;
Val.build(1,n);
for(int i=1;i<=n;i++)cin>>arr[i];
for(int i=1;i<=n;i++){
if(arr[i]!=1)vis[1]=1;
if(arr[i]>1&&Val.query(1,arr[i]-1)>last[arr[i]])vis[arr[i]]=1;
last[arr[i]]=i;
Val.updata(arr[i],arr[i],i);
}
for(int i=2;i<=n+1;i++){
if(Val.query(1,i-1)>last[i])vis[i]=1;
}
int Mex=1;
while(vis[Mex])Mex++;
cout<<Mex<<endl;
return 0;
}
|