3174. Clear Digits

1. Iterate through the string while maintaining a stack.
2. If the character is a letter, push it to the stack.
3. If the character is a digit:
   • Remove the last letter (if any) from the stack.
   • Do not push the digit itself.
4. The final stack contains the remaining string.

Python Implementation:

class Solution(object):
    def clearDigits(self, s):
        """
        :type s: str
        :rtype: str
        """
        stack = []
        
        for char in s:
            if char.isdigit():
                if stack:  # Remove the closest non-digit to the left
                    stack.pop()
            else:
                stack.append(char)
        
        return "".join(stack)

Complexity Analysis:

1. Time Complexity: O(n) → Single pass through s.
2. Space Complexity: O(n) → Stack stores at most n characters.

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