simple python solution
\nclass Solution(object):\n    def strWithout3a3b(self, A, B):\n        if A == 0 or B == 0:\n            return \'a\'*A +\'b\'*B\n        elif A>B:\n          
```\nclass Solution(object):\n    def strWithout3a3b(self, A, B):\n        if A == 0 or B == 0:\n            return \'a\'*A +\'b\'*B\n        elif A>B:\n            return \'aab\' + self.strWithout3a3b(A-2, B-1)\n        elif B>A:\n            return self.strWithout3a3b(A-1, B-2)+ \'abb\'\n        else:\n            return \'ab\' * A\n```
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