Program to find longest common prefix from list of strings in Python

Suppose we have a list of lowercase strings, we have to find the longest common prefix.

So, if the input is like ["antivirus", "anticlockwise", "antigravity"], then the output will be "anti"

To solve this, we will follow these steps −

sort the list words alphabetically

• prefix := a new list
• flag := 0
• for i in range 0 to size of words[0], do
  • for each j in words, do
    • if j[i] is not same as last element of prefix, then
      • delete last element from prefix
      • flag := 1
      • come out from the loop
  • if flag is same as 1, then
    • come out from the loop
• return string after concatenating all elements present in prefix array

Let us see the following implementation to get better understanding −

Example

 Live Demo

class Solution:
   def solve(self, words):
      words.sort()
      prefix = []
      flag = 0
      for i in range(len(words[0])):
         prefix.append(words[0][i])
         for j in words:
            if j[i] != prefix[-1]:
               prefix.pop()
               flag = 1
               break
         if flag == 1:
            break
         return ''.join(prefix)
ob = Solution()
words = ["antivirus", "anticlockwise", "antigravity"]
print(ob.solve(words))

Input

["antivirus", "anticlockwise", "antigravity"]

Output

anti

Arnab Chakraborty

Updated on: 06-Oct-2020

1K+ Views

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