We take the first string as our initial prefix and repeatedly prune it from the end whenever it doesn't match the start of the next string in the array.

1. If strs is empty, return "".
2. Set prefix = strs[0].
3. For each string s in strs[1:]:
   • While s does not start with prefix:
     • Shorten prefix by removing the last character.
     • If prefix becomes empty, return "".
4. Return prefix.

• Time Complexity: O(S), where S is the sum of all characters in all strings.
• Space Complexity: O(1).

def longest_common_prefix(strs):
    if not strs: return ""
    
    prefix = strs[0]
    for s in strs[1:]:
        while not s.startswith(prefix):
            prefix = prefix[:-1]
            if not prefix: return ""
            
    return prefix