1071. Leetcode Solution in Java

#web3 #crypto #blockchain #offers

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Description:
For two strings s and t, we say "t divides s" if and only if s = t + ... + t (i.e., t is concatenated with itself one or more times).

Given two strings str1 and str2, return the largest string x such that x divides both str1 and str2.

Example 1:

Input: str1 = "ABCABC", str2 = "ABC"
Output: "ABC"
Example 2:

Input: str1 = "ABABAB", str2 = "ABAB"
Output: "AB"
Example 3:

Input: str1 = "LEET", str2 = "CODE"
Output: ""

Constraints:

1 <= str1.length, str2.length <= 1000

str1 and str2 consist of English uppercase letters.

Solution:

class Solution {
  public String gcdOfStrings(String str1, String str2) {
    if (str1.length() < str2.length())
      return gcdOfStrings(str2, str1);
    if (!str1.startsWith(str2))
      return "";
    if (str2.isEmpty())
      return str1;
    return gcdOfStrings(str2, mod(str1, str2));
  }

  private String mod(String s1, final String s2) {
    while (s1.startsWith(s2))
      s1 = s1.substring(s2.length());
    return s1;
  }
}