func_code_string: #include <bits/stdc++.h>   using namespace std;   int main() {     long long t;     cin >> t;     while (t--) {       long long n, k;       cin >> n >> k;       vector<long long> p;       vector<long long> pre;       for (long long i = 0; i < n; i++) {         p.push_back(i + 1);       }       long long sum = 0;       for (long long i = 0; i < n; i++) {         sum += p[i];         pre.push_back(sum);       }       long long ind = lower_bound(pre.begin(), pre.end(), k) - pre.begin();       long long x = p[ind];       long long y = n - x - 1;       long long bb;       bb = y + (pre[ind] - k) + 1;       vector<char> ans;       for (long long i = 0; i < n; i++) {         if (i == y || i == bb)           ans.push_back( b );         else           ans.push_back( a );       }       for (int i = 0; i < n; i++) {         cout << ans[i];       }       cout << endl;     }     return 0;   }   