2937. Make Three Strings Equal

Problem Link

Description

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You are given three strings: s1, s2, and s3. In one operation you can choose one of these strings and delete its rightmost character. Note that you cannot completely empty a string.

Return the minimum number of operations required to make the strings equal. If it is impossible to make them equal, return -1.

 

Example 1:

Input: s1 = "abc", s2 = "abb", s3 = "ab"

Output: 2

Explanation: Deleting the rightmost character from both s1 and s2 will result in three equal strings.

Example 2:

Input: s1 = "dac", s2 = "bac", s3 = "cac"

Output: -1

Explanation: Since the first letters of s1 and s2 differ, they cannot be made equal.

 

Constraints:

• 1 <= s1.length, s2.length, s3.length <= 100
• s1, s2 and s3 consist only of lowercase English letters.

Solution

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Python3

class Solution:
    def findMinimumOperations(self, s1: str, s2: str, s3: str) -> int:
        n1, n2, n3 = len(s1), len(s2), len(s3)
        common = 0
        i = j = k = 0
        
        while i < n1 and j < n2 and k < n3:
            if s1[i] == s2[j] == s3[k]:
                common += 3
                i += 1
                j += 1
                k += 1
            else:
                break
        
        if common == 0: return -1
        
        return n1 + n2 + n3 - common