1768 Merge Strings Alternately

Approach 1 Two Pointers

\(O(m+n)\) time complexity, \(O(m+n)\) space complexity where \(m\) is the length of word1 and \(n\) is the length of word2

class Solution:
    def mergeAlternately(self, word1: str, word2: str) -> str:
        l1,r1 = 0,len(word1)
        l2,r2 = 0,len(word2)

        res = []
        while l1 < r1 or l2 < r2:
            if l1 < r1:
                res.append(word1[l1])
                l1 += 1
            if l2 < r2:
                res.append(word2[l2])
                l2 += 1

        return "".join(res)