# Generate a string consisting of characters ‘a’ and ‘b’ that satisfy the given conditions

Given two integers A and B, the task is to generate and print a string str such that:

1. str must only contain the characters ‘a’ and ‘b’.
2. str has length A + B and the occurrence of the character ‘a’ is equal to A and the occurrence of character ‘b’ is equal to B
3. The sub-strings “aaa” or “bbb” must not occur in str.

Note: For the given values of A and B, a valid string can always be generated.

Examples:

```Input: A = 1, B = 2
Output: abb
"abb", "bab" and "bba" are all valid strings.```
```Input: A = 4, B = 1
Output: aabaa ```

Approach:

• If occurrence(a) > occurrence(b) then append “aab”
• If occurrence(b) > occurrence(a) then append “bba”
• If occurrence(a) = occurrence(b) then append “ab”

Since we reduce the difference between the occurrences of ‘a’ and ‘b’ by at most 1 in each iteration so “bba” and “aab” are guaranteed not to be followed by “aab” and “bba” respectively.

Below is the implementation of the above approach:

## C++

 `// C++ implementation of the approach` `#include ` `using` `namespace` `std;`   `// Function to generate and print the required string` `void` `generateString(``int` `A, ``int` `B)` `{` `    ``string rt;` `    ``while` `(0 < A || 0 < B) {`   `        ``// More 'b', append "bba"` `        ``if` `(A < B) {` `            ``if` `(0 < B--)` `                ``rt.push_back(``'b'``);` `            ``if` `(0 < B--)` `                ``rt.push_back(``'b'``);` `            ``if` `(0 < A--)` `                ``rt.push_back(``'a'``);` `        ``}`   `        ``// More 'a', append "aab"` `        ``else` `if` `(B < A) {` `            ``if` `(0 < A--)` `                ``rt.push_back(``'a'``);` `            ``if` `(0 < A--)` `                ``rt.push_back(``'a'``);` `            ``if` `(0 < B--)` `                ``rt.push_back(``'b'``);` `        ``}`   `        ``// Equal number of 'a' and 'b'` `        ``// append "ab"` `        ``else` `{` `            ``if` `(0 < A--)` `                ``rt.push_back(``'a'``);` `            ``if` `(0 < B--)` `                ``rt.push_back(``'b'``);` `        ``}` `    ``}` `    ``cout << rt;` `}`   `// Driver code` `int` `main()` `{` `    ``int` `A = 2, B = 6;` `    ``generateString(A, B);`   `    ``return` `0;` `}`

## Java

 `// Java implementation of the approach` `class` `GFG ` `{`   `    ``// Function to generate and ` `    ``// print the required string` `    ``static` `void` `generateString(``int` `A, ``int` `B) ` `    ``{` `        ``String rt = ``""``;` `        ``while` `(``0` `< A || ``0` `< B) ` `        ``{`   `            ``// More 'b', append "bba"` `            ``if` `(A < B)` `            ``{` `                ``if` `(``0` `< B--)` `                ``{` `                    ``rt += (``'b'``);` `                ``}` `                ``if` `(``0` `< B--) ` `                ``{` `                    ``rt += (``'b'``);` `                ``}` `                ``if` `(``0` `< A--) ` `                ``{` `                    ``rt += (``'a'``);` `                ``}` `            ``} ` `            `  `            ``// More 'a', append "aab"` `            ``else` `if` `(B < A)` `            ``{` `                ``if` `(``0` `< A--) ` `                ``{` `                    ``rt += (``'a'``);` `                ``}` `                ``if` `(``0` `< A--) ` `                ``{` `                    ``rt += (``'a'``);` `                ``}` `                ``if` `(``0` `< B--) ` `                ``{` `                    ``rt += (``'b'``);` `                ``}` `            ``} ` `            `  `            ``// Equal number of 'a' and 'b'` `            ``// append "ab"` `            ``else` `            ``{` `                ``if` `(``0` `< A--) ` `                ``{` `                    ``rt += (``'a'``);` `                ``}` `                ``if` `(``0` `< B--) ` `                ``{` `                    ``rt += (``'b'``);` `                ``}` `            ``}` `        ``}` `        ``System.out.println(rt);` `    ``}`   `    ``// Driver code` `    ``public` `static` `void` `main(String[] args) ` `    ``{` `        ``int` `A = ``2``, B = ``6``;` `        ``generateString(A, B);` `    ``}` `} `   `// This code is contributed ` `// by PrinciRaj1992`

## Python 3

 `# Python 3 implementation of the approach`   `# Function to generate and print ` `# the required string` `def` `generateString(A, B):`   `    ``rt ``=` `""` `    ``while` `(``0` `< A ``or` `0` `< B) :`   `        ``# More 'b', append "bba"` `        ``if` `(A < B) :` `            ``if` `(``0` `< B):` `                ``rt ``=` `rt ``+``'b'` `                ``B ``-``=` `1` `            ``if` `(``0` `< B):` `                ``rt ``+``=` `'b'` `                ``B ``-``=` `1` `            ``if` `(``0` `< A):` `                ``rt ``+``=` `'a'` `                ``A ``-``=` `1`   `        ``# More 'a', append "aab"` `        ``elif` `(B < A):` `            ``if` `(``0` `< A):` `                ``rt ``+``=` `'a'` `                ``A ``-``=` `1` `            ``if` `(``0` `< A):` `                ``rt ``+``=` `'a'` `                ``A ``-``=` `1` `            ``if` `(``0` `< B):` `                ``rt ``+``=` `'b'` `                ``B ``-``=` `1`   `        ``# Equal number of 'a' and 'b'` `        ``# append "ab"` `        ``else` `:` `            ``if` `(``0` `< A):` `                ``rt ``+``=` `'a'` `                ``A ``-``=` `1` `            ``if` `(``0` `< B):` `                ``rt ``+``=` `'b'` `                ``B ``-``=` `1` `    ``print``(rt)`   `# Driver code` `if` `__name__ ``=``=` `"__main__"``:` `    `  `    ``A ``=` `2` `    ``B ``=` `6` `    ``generateString(A, B)`   `# This code is contributed by ita_c`

## C#

 `// C# implementation of the approach ` `using` `System;`   `class` `GFG ` `{ `   `    ``// Function to generate and ` `    ``// print the required string ` `    ``static` `void` `generateString(``int` `A, ``int` `B) ` `    ``{ ` `        ``string` `rt = ``""``; ` `        ``while` `(0 < A || 0 < B) ` `        ``{ `   `            ``// More 'b', append "bba" ` `            ``if` `(A < B) ` `            ``{ ` `                ``if` `(0 < B--) ` `                ``{ ` `                    ``rt += (``'b'``); ` `                ``} ` `                ``if` `(0 < B--) ` `                ``{ ` `                    ``rt += (``'b'``); ` `                ``} ` `                ``if` `(0 < A--) ` `                ``{ ` `                    ``rt += (``'a'``); ` `                ``} ` `            ``} ` `            `  `            ``// More 'a', append "aab" ` `            ``else` `if` `(B < A) ` `            ``{ ` `                ``if` `(0 < A--) ` `                ``{ ` `                    ``rt += (``'a'``); ` `                ``} ` `                ``if` `(0 < A--) ` `                ``{ ` `                    ``rt += (``'a'``); ` `                ``} ` `                ``if` `(0 < B--) ` `                ``{ ` `                    ``rt += (``'b'``); ` `                ``} ` `            ``} ` `            `  `            ``// Equal number of 'a' and 'b' ` `            ``// append "ab" ` `            ``else` `            ``{ ` `                ``if` `(0 < A--) ` `                ``{ ` `                    ``rt += (``'a'``); ` `                ``} ` `                ``if` `(0 < B--) ` `                ``{ ` `                    ``rt += (``'b'``); ` `                ``} ` `            ``} ` `        ``} ` `        ``Console.WriteLine(rt); ` `    ``} `   `    ``// Driver code ` `    ``public` `static` `void` `Main() ` `    ``{ ` `        ``int` `A = 2, B = 6; ` `        ``generateString(A, B); ` `    ``} ` `} `   `// This code is contributed by Ryuga`

## PHP

 ``

## Javascript

 ``

Output

`bbabbabb`

Complexity Analysis:

• Time Complexity: O(Max(a,b))
• Auxiliary Space: O(Max(a,b))

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