### Given integer n find the nth string in this sequence A , B , C , . . . , Z , AA , AB , AC , . . . , ZZ , AAA , AAB , . . . AAZ , ABA . . .

Given integer n find the nth string in this sequence A , B , C , . . . , Z , AA , AB , AC , . . . , ZZ , AAA , AAB , . . . AAZ , ABA . . .

Examples:

```Input: N
Output: Nth string

Input: 1
Output: A

Input: 704
Output: AAB

```

Approach:

1. We will be constructing nth string from back.
2. Make a string of 26 alphabets named alpha[]={A , B .. , Z}.
3. If n<=26 print alpha[n-1].
4. Else decrease n by 1 and add alpha[n%26] to string and repeat above steps for n/26 till n>0.
5. Reverse the generated string.

``````#include <bits/stdc++.h>

using namespace std;

string findString( int n)
{
string alpha;// string of 26 alphabets from A to Z.

for(char i='A';i<='Z';i++)
alpha += i;

string ans;
//If n<=26 we can directly tell the nth string
if(n <= 26)
{
ans += alpha[n-1];
return ans;
}
while( n > 0 )
{
ans += alpha[(--n)%26];
n = n/26;
}
reverse ( ans.begin() , ans.end() );
return ans;
}

int main()
{
int n=4;
//cin>>n;
cout<<findString(n);
return 0;
}
//Output : D``````