//Utkarsh.25dec #include <bits/stdc++.h> #define ll long long int #define pb push_back #define mp make_pair #define mod 1000000007 #define vl vector <ll> #define all(c) (c).begin(),(c).end() using namespace std; ll power(ll a,ll b) {ll res=1;a%=mod; assert(b>=0); for(;b;b>>=1){if(b&1)res=res*a%mod;a=a*a%mod;}return res;} ll modInverse(ll a){return power(a,mod-2);} const int N=500023; bool vis[N]; vector <int> adj[N]; long long readInt(long long l,long long r,char endd){ long long x=0; int cnt=0; int fi=-1; bool is_neg=false; while(true){ char g=getchar(); if(g=='-'){ assert(fi==-1); is_neg=true; continue; } if('0'<=g && g<='9'){ x*=10; x+=g-'0'; if(cnt==0){ fi=g-'0'; } cnt++; assert(fi!=0 || cnt==1); assert(fi!=0 || is_neg==false); assert(!(cnt>19 || ( cnt==19 && fi>1) )); } else if(g==endd){ if(is_neg){ x= -x; } if(!(l <= x && x <= r)) { cerr << l << ' ' << r << ' ' << x << '\n'; assert(1 == 0); } return x; } else { assert(false); } } } string readString(int l,int r,char endd){ string ret=""; int cnt=0; while(true){ char g=getchar(); assert(g!=-1); if(g==endd){ break; } cnt++; ret+=g; } assert(l<=cnt && cnt<=r); return ret; } long long readIntSp(long long l,long long r){ return readInt(l,r,' '); } long long readIntLn(long long l,long long r){ return readInt(l,r,'\n'); } string readStringLn(int l,int r){ return readString(l,r,'\n'); } string readStringSp(int l,int r){ return readString(l,r,' '); } void solve() { int n=readInt(1,100000,'\n'); string s=readString(n,n,'\n'); int freq[30]={0}; for(auto ch:s) { assert(ch>='a' && ch<='z'); freq[ch-'a']++; } char ans[n+1]; set <int> c1,c2,c3; for(int i=1;i<=n;i++) { if(i%3==1) c1.insert(i); if(i%3==2) c2.insert(i); if(i%3==0) c3.insert(i); } vector <pair<int,char>> v; for(char ch='a';ch<='z';ch++) v.pb(mp(freq[ch-'a'],ch)); sort(all(v)); reverse(all(v)); int limit=(n+2)/3; int bad=0; for(char ch='a';ch<='z';ch++) { if(freq[ch-'a']>limit) { cout<<"NO\n"; return; } if(freq[ch-'a']==limit) bad++; } int afford=n%3; if(afford==0) afford=3; if(bad>afford) { cout<<"NO\n"; return; } cout<<"YES\n"; for(auto it:v) { // cout<<it.first<<' '<<it.second<<'\n'; if(it.first==limit) { if(c1.size()==limit) { while(c1.size()>0) { auto it2=c1.begin(); ans[(*it2)]=it.second; c1.erase(it2); } continue; } if(c2.size()==limit) { while(c2.size()>0) { auto it2=c2.begin(); ans[(*it2)]=it.second; c2.erase(it2); } continue; } if(c3.size()==limit) { while(c3.size()>0) { auto it2=c3.begin(); ans[(*it2)]=it.second; c3.erase(it2); } continue; } } else { for(int i=1;i<=it.first;i++) { if(c3.size()>0) { auto it2=c3.begin(); ans[(*it2)]=it.second; c3.erase(it2); continue; } if(c2.size()>0) { auto it2=c2.begin(); ans[(*it2)]=it.second; c2.erase(it2); continue; } if(c1.size()>0) { auto it2=c1.begin(); ans[(*it2)]=it.second; c1.erase(it2); continue; } } } } for(int i=1;i<=n;i++) cout<<ans[i]; cout<<'\n'; } int main() { #ifndef ONLINE_JUDGE freopen("input.txt", "r", stdin); freopen("output.txt", "w", stdout); #endif ios_base::sync_with_stdio(false); cin.tie(NULL),cout.tie(NULL); int T=readInt(1,100000,'\n'); while(T--) solve(); assert(getchar()==-1); cerr << "Time : " << 1000 * ((double)clock()) / (double)CLOCKS_PER_SEC << "ms\n"; }