1768 - Merge Strings Alternatively

The 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.

Examples:

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

Understanding the problem

This problem is asking us to take two words and build a new one from iterating each char at the same position in both words and merge them together.

Code

function mergeAlternately(word1: string, word2: string): string {
  const chars = [];
  // Loop over the max word length
  for (let i = 0; i < Math.max(word1.length, word2.length); i++) {
    // if the index is in bounds of word1 push that char first
    if (i < word1.length) chars.push(word1[i]);
    // if the index is in bounds of word 2 push that char secondly
    if (i < word2.length) chars.push(word2[i]);
    // this will also allow for the example where one word is longer than the other.
  }
  // return the array as a string.
  return chars.join("");
}

Code Explanation

This solution is pretty simple and well documented. See above.

Key takeaways

1. Remember the data we get give in our inputs, like in this example we can iterate over both by using Math.max() to get the largest word length and traverse the array accordingly.
2. Keep it simple wins.