input: Write a python function to find the longest common prefix among an array of strings.
  assert longest_common_prefix(["flower", "flow", "flight"]) == "fl"
  assert longest_common_prefix(["dog", "racecar", "car"]) == ""
  assert longest_common_prefix(["interspecies", "interstellar", "interstate"]) == "inters"
output: def longest_common_prefix(strs):
      if not strs:
          return ""
      
      min_str = min(strs, key=len)
      
      for i, char in enumerate(min_str):
          for other in strs:
              if other[i] != char:
                  return min_str[:i]
      
      return min_str