t = int(input())
def bin_search(low, high, target):
while low < high:
mid = low + (high - low)//2
if (mid * (mid + 1))//2 > target:
high = mid
else:
low = mid+1
res = mid
return low
while t > 0:
maxi = int(2e9+7)
n, k = [int(i) for i in input().split(" ")]
r = bin_search(0, maxi, k)
r -= 1
return_sum = (r * (r+1))//2
if return_sum == k:
first_shift = n-1-r
else:
first_shift = n-2-r
if return_sum == k:
second_shift = first_shift+1
else:
second_shift = n-1-(k-return_sum-1)
ans = ['a'] * n
ans[first_shift] = 'b'
ans[second_shift] = 'b'
print("".join(ans))
t -= 1#include<bits/stdc++.h>
#define io ios::sync_with_stdio(false),cin.tie(0),cout.tie(0)
#define pb push_back
#define pf push_front
#define fi first
#define se second
#define db double
#define endl "\n"
#define ll long long
#define pii pair<int,int>
using namespace std;
const int N =1e5+10;
void solve(){
ll n,k;
cin>>n>>k;
//1 2 3 4 5 6
ll l=0,r=n+1;
while(l+1!=r){
ll mid=l+r>>1;
if((mid+1)*mid/2>=k) r=mid;
else l=mid;
}
int pos1=n-r;//1-n-1 2-n-2 5-n-5
int pos2=k-(ll)r*(r-1)/2;//1-n 2-n-1
pos2=n+1-pos2;
string s(n,'a');
s[pos1-1]='b';
s[pos2-1]='b';
cout<<s<<endl;
}
int main()
{
io;
int t;
cin>>t;
while(t--){
solve();
}
return 0;
} 1302. Deepest Leaves Sum | 1209. Remove All Adjacent Duplicates in String II |
994. Rotting Oranges | 983. Minimum Cost For Tickets |
973. K Closest Points to Origin | 969. Pancake Sorting |
967. Numbers With Same Consecutive Differences | 957. Prison Cells After N Days |
946. Validate Stack Sequences | 921. Minimum Add to Make Parentheses Valid |
881. Boats to Save People | 497. Random Point in Non-overlapping Rectangles |
528. Random Pick with Weight | 470. Implement Rand10() Using Rand7() |
866. Prime Palindrome | 1516A - Tit for Tat |
622. Design Circular Queue | 814. Binary Tree Pruning |
791. Custom Sort String | 787. Cheapest Flights Within K Stops |
779. K-th Symbol in Grammar | 701. Insert into a Binary Search Tree |
429. N-ary Tree Level Order Traversal | 739. Daily Temperatures |
647. Palindromic Substrings | 583. Delete Operation for Two Strings |
518. Coin Change 2 | 516. Longest Palindromic Subsequence |
468. Validate IP Address | 450. Delete Node in a BST |