Python Basics簡単

Remove adjacent duplicates recursively

Detailed guide and Python implementation for the 'Remove adjacent duplicates recursively' problem.

問題提起

簡単

Write a function remove_adjacent_duplicates(s) that recursively removes all adjacent duplicate characters from the string s until no adjacent duplicates remain. In each pass, remove all pairs of consecutive identical characters, then repeat the process on the resulting string until it stabilizes. Return the final string.

制約
  • 0 <= len(s) <= 1000
  • s contains only lowercase English letters

Example 1
Input
s = 'aabccba'
Output
'a'
Explanation

First pass: remove 'aa' and 'cc' -> 'bba'. Second pass: remove 'bb' -> 'a'. No more adjacent duplicates.

Example 2
Input
s = 'abcddcba'
Output
''
Explanation

Remove 'dd' -> 'abccba'. Remove 'cc' -> 'abba'. Remove 'bb' -> 'aa'. Remove 'aa' -> ''. Empty string.

Example 3
Input
s = 'abcd'
Output
'abcd'
Explanation

No adjacent duplicates exist, so the string remains unchanged.

Need a Hint?
Consider using Recursion-specific data structures like sets or heaps.
Edge Cases to Watch
  • Empty input structures
  • Single element inputs
  • Large numerical bounds

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