[leetcode] 1768. Merge Strings Alternately _ Algorithm Problem Solve for python

1. Problem

1768. Merge Strings Alternately

You are given two strings word1 and word2. Merge the strings by adding letters in alternating order, starting with word1. If a string is longer than the other, append the additional letters onto the end of the merged string.

Return the merged string.

Example 1:

Input: word1 = "abc", word2 = "pqr"
Output: "apbqcr"
Explanation: The merged string will be merged as so:
word1:  a   b   c
word2:    p   q   r
merged: a p b q c r

Example 2:

Input: word1 = "ab", word2 = "pqrs"
Output: "apbqrs"
Explanation: Notice that as word2 is longer, "rs" is appended to the end.
word1:  a   b 
word2:    p   q   r   s
merged: a p b q   r   s

Example 3:

Input: word1 = "abcd", word2 = "pq"
Output: "apbqcd"
Explanation: Notice that as word1 is longer, "cd" is appended to the end.
word1:  a   b   c   d
word2:    p   q 
merged: a p b q c   d

Constraints:

• 1 <= word1.length, word2.length <= 100
• word1 and word2 consist of lowercase English letters.

2. Solution

I solved this problem like this.

• Complexity
  • Time complexity : O(N)
  • Space complexity : O(N)
• Step
  • Using zip and append string to answer.

class Solution:
    def mergeAlternately(self, word1: str, word2: str) -> str:
        answer = ""
        min_size = min(len(word1), len(word2))
        for x, y in zip(word1, word2):
            answer += x + y
        return answer + word1[min_size:] + word2[min_size:]