2309. Greatest English Letter in Upper and Lower Case
IntuitionApproachComplexity
Time complexity:

Space complexity:
Code
# Intuition
<!-- Describe your first thoughts on how to solve this problem. -->

# Approach
<!-- Describe your approach to solving the problem. -->

# Complexity
- Time complexity:
<!-- Add your time complexity here, e.g. $$O(n)$$ -->

- Space complexity:
<!-- Add your space complexity here, e.g. $$O(n)$$ -->

# Code
```python3 []
class Solution:
    def greatestLetter(self, s: str) -> str:
        for c in range(25, -1, -1):  # Iterate from 'Z' to 'A'
            upper = chr(c + 65)  # Uppercase letter
            lower = chr(c + 97)  # Lowercase letter
            if upper in s and lower in s:
                return upper
        return ""

```
['Python3']