# Longest Common Prefix

def longestCommonPrefix(words): # Input: List of Strings

if not words: # if words is empty

return "" # return empty string

if len(words) == 1: # if words has only one element

return words[0] # return the element

prefix = words[0] # set prefix to the first element

for i in range(1, len(words)): # for each element in words

while words[i].find(prefix) != 0: # while the element does not start with prefix

prefix = prefix[:-1] # remove the last character of prefix

if prefix == "": # if prefix is empty

return "" # return empty string

return prefix # Output: String of the longest common prefix

# Driver to test the function

print(longestCommonPrefix(["flower","flow","flight"])) # Output: "fl"

print(longestCommonPrefix(["dog","racecar","car"])) # Output: ""

print(longestCommonPrefix(["a"])) # Output: "a"

print(longestCommonPrefix(["aa","a"])) # Output: "a"