Is Merge Strings Alternately easy or hard?

Merge Strings Alternately is classified as an Easy problem on LeetCode with a high acceptance rate above 80%. It mainly tests basic string traversal, pointer management, and careful handling of leftover characters.

Merge Strings Alternately Python/Java solution

In Python or Java, iterate with two indices and append characters to a result builder. Python typically uses a list or string concatenation with join, while Java uses StringBuilder for efficient appends. Both implementations run in O(n + m) time.

How to solve Merge Strings Alternately in O(n)?

Use two indices starting at the beginning of each string. Append characters alternately while incrementing the pointers. Continue until both indices reach the end, appending leftover characters if one string is longer. This ensures each character is visited only once, giving O(n + m) time complexity.

What is the best approach for Merge Strings Alternately?

The best approach uses two pointers (or indices) to iterate through both strings and append characters alternately. Each pointer advances independently and remaining characters from the longer string are appended at the end. This runs in O(n + m) time with O(1) extra space.

Is Merge Strings Alternately asked at Google/Amazon/Meta?

Merge Strings Alternately appears in coding interview preparation sets and is commonly used as an introductory string or two‑pointer problem. Similar alternating merge patterns show up in interviews at companies like Amazon and Google to test basic string manipulation and pointer control.

What data structure is used in Merge Strings Alternately?

The problem mainly uses basic string operations and the two‑pointer technique. Some implementations use a mutable string builder or character array to efficiently append characters during iteration.

What is the time complexity of Merge Strings Alternately?

The optimal solution processes each character from both strings exactly once. If the string lengths are n and m, the time complexity is O(n + m). Space complexity is O(1) excluding the output string.

Description Hints 1 Solution Video 4:22

1768. Merge Strings Alternately

Easy82.1% acceptance11 companies

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: