Problem

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:

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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:

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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:

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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.

Solve

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class Solution:
    def mergeAlternately(self, word1: str, word2: str) -> str:
        i , j = 0 , 0
        last = 2
        res = ""

        while i < len(word1) or j < len(word2):
            if last == 2:
                if  i < len(word1):
                    res += word1[i]
                else:
                    res += ""
                i += 1
                last = 1
            
            if last == 1:
                if j < len(word2):
                    res += word2[j]
                else:
                    res += ""
                j+=1
                last = 2
        return res