Merge Strings Alternately

LeetCode #1768

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.

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:

• 1 <= word1.length, word2.length <= 100
• word1 and word2 consist of lowercase English letters.

JAVA CODE

Optimal Solution Merge Strings Alternately

class Solution {
    public String mergeAlternately(String word1, String word2) {
        
        int i = 0, j = 0, k = 0;
        String mergedString = "";
        while (i < word1.length() && j < word2.length()){
            if (k % 2 == 0) {
                mergedString += word1.charAt(i++);
                k++;
            }else{
                mergedString += word2.charAt(j++);
                k++;
            }
        }

        while (i < word1.length()) {
            mergedString += word1.charAt(i++);
        }
        while (j < word2.length()) {
            mergedString += word2.charAt(j++);
        }
        return mergedString;
    }
}