> ## Documentation Index
> Fetch the complete documentation index at: https://leetcode-py.wisl.dev/llms.txt
> Use this file to discover all available pages before exploring further.

> ## Agent Instructions
> leetcode-py is a Python LeetCode practice environment generator with one CLI: lcpy. It is not a service or platform.
> Each problem is a directory under leetcode/ with README.md, solution.py, test_solution.py, helpers.py, and playground.ipynb. lcpy gen creates them from JSON templates bundled with the package.
> Examples are backed by tests; copy them verbatim.

# Merge Strings Alternately Python Solution

> Tested Python solution for LeetCode 1768 with 13 pytest cases. Generate a practice environment with lcpy.

LeetCode 1768, Easy. Topics: Two Pointers, String. [View on LeetCode](https://leetcode.com/problems/merge-strings-alternately/description/).

Generate this problem as a practice environment: tested reference solution, 13 [parametrized pytest cases](/practice/testing), and a playground notebook:

```bash theme={"theme":{"light":"github-light","dark":"github-dark"}}
lcpy gen -n 1768   # by problem number
lcpy gen -s merge_strings_alternately   # by problem name
```

## 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.*

### Examples

```
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
```

```
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
```

```
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.

## Solution

Reference implementation from [solution.py on GitHub](https://github.com/wislertt/leetcode-py/blob/main/leetcode/merge_strings_alternately/solution.py), full suite in [test\_solution.py](https://github.com/wislertt/leetcode-py/blob/main/leetcode/merge_strings_alternately/test_solution.py):

```python theme={"theme":{"light":"github-light","dark":"github-dark"}}
class Solution:
    # Time: O(n + m)
    # Space: O(n + m)
    def merge_alternately(self, word1: str, word2: str) -> str:
        result: list[str] = []
        i = 0
        n, m = len(word1), len(word2)

        while i < n or i < m:
            if i < n:
                result.append(word1[i])
            if i < m:
                result.append(word2[i])
            i += 1

        return "".join(result)
```

## Complexity

| Time     | Space    |
| -------- | -------- |
| O(n + m) | O(n + m) |

## Tags

[NeetCode 250](/catalog/neetcode-250), [NeetCode All](/catalog/neetcode).