You are given two ints: N and K. Lun the dog is interested in strings that satisfy the following conditions:
- The string has exactly N characters, each of which is either 'A' or 'B'.
- The string s has exactly K pairs (i, j) (0 <= i < j <= N-1) such that s[i] = 'A' and s[j] = 'B'.
If there exists a string that satisfies the conditions, find and return any such string. Otherwise, return an empty string.
|Method signature:||String createString(int N, int K)|
|(be sure your method is public)|
|-||N will be between 2 and 50, inclusive.|
|-||K will be between 0 and N(N-1)/2, inclusive.|
|This string has exactly two pairs (i, j) mentioned in the statement: (0, 1) and (0, 2).|
|Please note that there are valid test cases with K = 0.|
|Five characters is too short for this value of K.|
|Please note that this is an example of a solution; other valid solutions will also be accepted.|
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