func_code_string: #include <bits/stdc++.h>   using namespace std;   template<typename A, typename B> ostream& operator<<(ostream &os, const pair<A, B> &p) { return os <<  (  << p.first <<  ,   << p.second <<  ) ; }   template<typename T_container, typename T = typename enable_if<!is_same<T_container, string>::value, typename T_container::value_type>::type> ostream& operator<<(ostream &os, const T_container &v) { os <<  { ; string sep; for (const T &x : v) os << sep << x, sep =  ,  ; return os <<  } ; }   void dbg_out() { cerr << endl; }   template<typename Head, typename... Tail> void dbg_out(Head H, Tail... T) { cerr <<     << H; dbg_out(T...); }   #ifdef WA_DEBUG   #define dbg(...) cerr <<  (  << #__VA_ARGS__ <<  ): , dbg_out(__VA_ARGS__)   #else   #define dbg(...)   #endif      using ll  = long long;   using ull = unsigned long long;   #define pb push_back   #define fi first   #define se second   #define rep(i,a,b) for(int i=int(a);i<=(int)(b);i++)   #define per(i,a,b) for(int i=int(a);i>=(int)(b);i--)   const int mod  = 1e9+7;   const int inf  = 0x3f3f3f3f;   const int maxn = 1e5+10;   int main() {   #ifndef WA_DEBUG       ios::sync_with_stdio(false);cin.tie(nullptr);   #endif       int _;       cin>>_;       while(_--) {           int n;           cin>>n;            string a,b,c;           cin>>a>>b>>c;           int lena=0,lenb=0,lenc=0;           rep(i,1,3*n) {               vector<int> cnt(2,0);               if(lena<2*n) cnt[a[lena]- 0 ]++;               if(lenb<2*n) cnt[b[lenb]- 0 ]++;               if(lenc<2*n) cnt[c[lenc]- 0 ]++;               if(cnt[0]>cnt[1]) {                   cout<<0;                   if(lena<2*n&&a[lena]== 0 ) lena++;                   if(lenb<2*n&&b[lenb]== 0 ) lenb++;                   if(lenc<2*n&&c[lenc]== 0 ) lenc++;               }               else {                   cout<<1;                   if(lena<2*n&&a[lena]== 1 ) lena++;                   if(lenb<2*n&&b[lenb]== 1 ) lenb++;                   if(lenc<2*n&&c[lenc]== 1 ) lenc++;               }               if(lena==2*n||lenb==2*n||lenc==2*n) {                   break;               }           }           if(lena==2*n) {               if(lenb>lenc) {                   while(lenb<2*n) cout<<b[lenb++];               }               else {                   while(lenc<2*n) cout<<c[lenc++];               }           }           else if(lenb==2*n) {               if(lena>lenc) {                   while(lena<2*n) cout<<a[lena++];               }               else {                   while(lenc<2*n) cout<<c[lenc++];               }           }           else {               if(lena>lenb) {                   while(lena<2*n) cout<<a[lena++];               }               else {                   while(lenb<2*n) cout<<b[lenb++];               }           }           cout<<  n ;       }       return 0;   }   