[LeetCode] 1768. Merge Strings Alternately [Java]

1768. Merge Strings Alternately

https://leetcode.com/problems/merge-strings-alternately

문제

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.

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문자열 두 개의 문자들을 번갈아 옮겨 합쳐 하나의 문자열로 만드는 문제였다. 각 단어를 동시에 순회하는데, 단어별로 사용하는 인덱스는 i, j로 나누어 사용하였다. i, j 둘중 하나가 문자끝에 도달하면 반복을 종료하고, 아직 문자끝에 도달하지 못한 인덱스값을 이용해서 해당 단어이 나머지 문자들을 substring 메서드를 통해서 옮겨준다.

class Solution {
    public String mergeAlternately(String word1, String word2) {
        StringBuilder sb = new StringBuilder();

        int i = 0, j = 0;
        while(i<word1.length() && j<word2.length()){
            sb.append(word1.charAt(i));
            sb.append(word2.charAt(j));

            i++;
            j++;
        }

        if(i!=word1.length()){
            sb.append(word1.substring(i));
        }

        if(j!=word2.length()){
            sb.append(word2.substring(j));
        }

        return sb.toString();
    }
}