1768. 交替合并字符串

1768. 交替合并字符串

      class Solution {
          public String mergeAlternately(String word1, String word2) {
            StringBuilder ans = new StringBuilder();
            int len1 = word1.length();
            int len2 = word2.length();
            int i = 0, j = 0;
            int k = 0;
            while (i < len1 && j < len2) {
                if(k % 2 == 0) {
                    ans.append(word1.charAt(i));
                    ++i;
                }
                else {
                    ans.append(word2.charAt(j));
                    ++j;
                }
                ++k;
            }
            if (i < len1) {
                ans.append(word1.substring(i, len1));
            }
            if (j < len2) {
                ans.append(word2.substring(j, len2));
            }
            return ans.toString() ;
          }
      }