LeetCode 1768. Merge Strings Alternately

Description

https://leetcode.com/problems/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.

Explanation

Similar to merge arrays or linked lists.

Python Solution

class Solution:
def mergeAlternately(self, word1: str, word2: str) -> str:
result = ""

i = 0
j = 0

while i < len(word1) and j < len(word2):
if len(result) % 2 == 0:
result += word1[i]
i += 1
else:
result += word2[j]
j += 1

while i < len(word1):
result += word1[i]
i += 1

while j < len(word2):
result += word2[j]
j += 1

return result
• Time Complexity: O(N)
• Space Complexity: O(N)