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Repeated Substring Pattern-LeetCode#459

459. Repeated Substring Pattern

Given a non-empty string check if it can be constructed by taking a substring of it and appending multiple copies of the substring together. You may assume the given string consists of lowercase English letters only and its length will not exceed 10000.

 

Example 1:

Input: "abab"
Output: True
Explanation: It's the substring "ab" twice.

Example 2:

Input: "aba"
Output: False

Example 3:

Input: "abcabcabcabc"
Output: True
Explanation: It's the substring "abc" four times. (And the substring "abcabc" twice.)
思路:从原字符串长度的一半遍历到1,如果当前长度能被总长度整除,说明可以分成若干个子字符串,我们将这些子字符串拼接起来看跟原字符串是否相等。
代码如下:
public class RepeatedSubstringPattern {
    public boolean repeatedSubstringPattern(String s) {
        int l = s.length();
        for (int i = l / 2; i >= 1; i--) {
            if (l % i == 0) {
                String temp = s.substring(0, i);
                StringBuilder stringBuilder = new StringBuilder();
                for (int j = 0; j < l / i; j++) {
                    stringBuilder.append(temp);
                }
                if (stringBuilder.toString().equals(s)) return true;
            }
        }

        return false;
    }
}

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