Merge Strings Alternately

Two Pointers (Zip)

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Watch: String Methods in Python · Bro Code · 2022

Asked in interviews at

5 in the last 6 months

Google
Microsoft
Amazon
Meta
Bloomberg
Wells Fargo
Uber
IBM
Zoho
Infosys
Oracle

Community-reported company tags from leetcode-company-wise-problems (updated 2026-10-08). Bar shows how often each company asks it.

Problem

Problem Statement

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.

Input / Output

Input:  word1 = "abc", word2 = "pqr"
Output: "apbqcr"

Input:  word1 = "ab", word2 = "pqrs"
Output: "apbqrs"

Input:  word1 = "abcd", word2 = "pq"
Output: "apbqcd"

Constraints

1 ≤ word1.length, word2.length ≤ 100
word1 and word2 consist of lowercase English letters

Understanding the Problem

Take one char from word1, then one from word2, repeat
When one runs out, append the rest of the other

Edge Cases

Equal lengths → perfect interleave
One much longer → tail appended as-is

Solve it yourself before you look

Reading the solution first feels like progress, but it makes the next similar problem — and the interview version — much harder, because you skipped the part where you figure it out. Give it an honest 20–30 minutes. Stuck? Re-read the pattern, watch the concept video, or try the brute force first.

Hidden: approach · solution code

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