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;
}