1768.交替合并字符串

class Solution {
    public String mergeAlternately(String word1, String word2) {
        int len1 = word1.length(), len2 = word2.length();
        int index = 0;
        char[] result = new char[len1 + len2];
        for(int i = 0; i < len1 || i < len2; i++){
            if(i < len1) result[index++] = word1.charAt(i);
            if(i < len2) result[index++] = word2.charAt(i);
        }
        return new String(result);
    }
}