~~Edit: Found it, thanks @nitindhemiwal : https://www.[Geeks4Geeks].org/recursively-remove-adjacent-duplicates-given-string/~~\n\nEdit2: Actually it\'s not it, we want the shortest, not just any.\n\n---\n\nA friend had this question in an Oracle interview:\n\n**Input**: An array of characters, example: [a,a,b,b,b,a,c]\n**Ouput**: Smallest length reduced form after removing duplicates step by step: [c]\n\naabbbac ---remove all **b**---> aaac ---remove all **a**---> c\nabccbaa ---remove all **c**---> abbaa ---remove all **b**---> aaa --> ""\naabccba ---remove all **c**---> aabba ---remove all **b**---> aaa -> []\naabbcca -> aacca -> aaa -> ""\naaaacddddcappp -> aaaaccappp -> aaaaappp -> ""\n\nDoes anyone know if it\'s similar to an existing leetcode question? I couldn\'t find the solution, but interviewer hinted that it\'s about using a stack.

~~Edit: Found it, thanks @nitindhemiwal : https://www.[Geeks4Geeks].org/recursively-remove-adjacent-duplicates-given-string/~~\n\nEdit2: Actually it\'s not it, 