Submission #24046495

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Source Code Expand

#include<iostream>
#include<set>
#include<vector>
#include<deque>
using namespace std;
int N;
int A[1<<17];
set<int>id[1<<17];
int cnt[1<<17];
vector<int>ans;
set<int>pre;
main()
{
	cin>>N;
	for(int i=0;i<N;i++)
	{
		cin>>A[i];
		A[i]--;
		cnt[A[i]]++;
		pre.insert(i);
	}
	if(N==2)
	{
		cout<<-1<<endl;
		return 0;
	}
	for(int i=0;i<N;i++)id[cnt[i]].insert(i);
	while(!pre.empty())
	{
		int u;
		bool flag=false;
		if(pre.size()==3&&id[1].size()==2)
		{
			int x=*id[1].begin(),y=*++id[1].begin();
			if(A[x]==y&&A[y]==x)flag=true;
		}
		if(flag)
		{
			if(ans.empty()||A[ans.back()]!=*id[1].begin())u=*id[1].begin();
			else u=*++id[1].begin();
		}
		else if(!id[pre.size()-1].empty())u=*id[pre.size()-1].begin();
		else
		{
			if(ans.empty()||A[ans.back()]!=*pre.begin())u=*pre.begin();
			else u=*++pre.begin();
		}
		ans.push_back(u);
		pre.erase(u);
		id[cnt[u]].erase(u);
		if(id[cnt[A[u]]].find(A[u])!=id[cnt[A[u]]].end())
		{
			id[cnt[A[u]]].erase(A[u]);
			cnt[A[u]]--;
			id[cnt[A[u]]].insert(A[u]);
		}
	}
	for(int i=0;i<N;i++)cout<<ans[i]+1<<(i+1==N?"\n":" ");
}

Submission Info

Compile Error

./Main.cpp:12:6: warning: ISO C++ forbids declaration of ‘main’ with no type [-Wreturn-type]
   12 | main()
      |      ^

Judge Result