Restoring the Permutation(思维+multiset模拟）

https://codeforces.com/contest/1506/problem/E

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思路：字典序最小和最大比较好贪。

最大就是找剩下集合中小于当前最大数的第一个数。扔进multiset里二分然后对其位置-1即可。

#include<iostream>
#include<vector>
#include<queue>
#include<cstring>
#include<cmath>
#include<map>
#include<set>
#include<cstdio>
#include<algorithm>
#define debug(a) cout<<#a<<"="<<a<<endl;
using namespace std;
const int maxn=2e5+1000;
typedef long long LL;
inline LL read(){LL x=0,f=1;char ch=getchar();	while (!isdigit(ch)){if (ch=='-') f=-1;ch=getchar();}while (isdigit(ch)){x=x*10+ch-48;ch=getchar();}
return x*f;}
multiset<LL>s1,s2;
multiset<LL>::iterator it;
LL a[maxn];
bool vis[maxn];
vector<LL>ans1,ans2;
int main(void)
{
  cin.tie(0);std::ios::sync_with_stdio(false);
  LL t;cin>>t;
  while(t--){
    s1.clear();s2.clear();
    ans1.clear();ans2.clear();
    LL n;cin>>n;
    for(LL i=0;i<n+10;i++) vis[i]=0;
    for(LL i=1;i<=n;i++) s1.insert(i),s2.insert(i);
    for(LL i=1;i<=n;i++) cin>>a[i];
    LL maxv=0;
    for(LL i=1;i<=n;i++){
        if(!vis[a[i]]){
           ans1.push_back(a[i]);
            ans2.push_back(a[i]);
            vis[a[i]]=true;
            s1.erase(a[i]);
            s2.erase(a[i]);
            maxv=max(maxv,a[i]);
        }
        else if(vis[a[i]]){
            LL temp=(*s1.begin());
            s1.erase(temp);
            ans1.push_back(temp);
               it=s2.lower_bound(maxv);
               it--;
               ans2.push_back(*it);
               s2.erase(*it);
        }
    }
    for(auto i:ans1){
        cout<<i<<" ";
    }
    cout<<"\n";
    for(auto i:ans2){
        cout<<i<<" ";
    }
    cout<<"\n";
  }
return 0;
}