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1768. Merge Strings Alternately 👍

  • Time: $O(n)$
  • Space: $O(n)$
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class Solution {
 public:
  string mergeAlternately(string word1, string word2) {
    const int n = min(word1.length(), word2.length());
    string prefix;

    for (int i = 0; i < n; ++i) {
      prefix += word1[i];
      prefix += word2[i];
    }

    return prefix + word1.substr(n) + word2.substr(n);
  }
};

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class Solution {
  public String mergeAlternately(String word1, String word2) {
    final int n = Math.min(word1.length(), word2.length());
    StringBuilder sb = new StringBuilder();

    for (int i = 0; i < n; ++i) {
      sb.append(word1.charAt(i));
      sb.append(word2.charAt(i));
    }

    return sb.append(word1.substring(n)).append(word2.substring(n)).toString();
  }
}

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class Solution:
  def mergeAlternately(self, word1: str, word2: str) -> str:
    return ''.join(a + b for a, b in zip_longest(word1, word2, fillvalue=''))