Codeforces Round #677 (Div. 3) D/1433D Districts Connection

https://codeforces.com/contest/1433/problem/D

找两个不同权值的节点A、B连起来，所有与A不同权值的连到A上，相同的连到B上。

#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=5e3+100;
typedef long long LL;
LL a[maxn];
int main(void)
{
  cin.tie(0);std::ios::sync_with_stdio(false);
  LL t;cin>>t;
  while(t--)
  {
  	LL n;cin>>n;
  	for(LL i=1;i<=n;i++) cin>>a[i];
  	LL idx=-1;
  	vector<pair<LL,LL>>pr;
  	for(LL i=2;i<=n;i++)
  	{
  		if(a[i]!=a[1]){
  			pr.push_back({1,i});
			idx=i;
		}
	}
	if(idx==-1) {
		cout<<"NO"<<endl;
		continue;
	}
	else{
		for(LL i=2;i<=n;i++)
		{
			if(a[i]==a[1]){
				pr.push_back({idx,i});
			}
		}
		cout<<"YES"<<endl;
		for(auto i:pr){
			cout<<(i.first)<<" "<<(i.second)<<endl;
		}
	}
  }
return 0;
}