Write LeetCode Post " LeetCode : 459. Repeated Substring Pattern "

_posts/2023-10-08-LeetCode-Repeated-Substring-Pattern.md

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+---
+layout: post
+title: " LeetCode : 459. Repeated Substring Pattern "
+categories: LeetCode
+author: goodGid
+use_math: true
+---
+* content
+{:toc}
+
+## [459. Repeated Substring Pattern](https://leetcode.com/problems/repeated-substring-pattern)
+
+### Problem
+
+```
+Given a string s, check if it can be constructed by taking a substring of it and appending multiple copies of the substring together.
+```
+
+
+---
+
+### Example
+
+```
+Input: s = "abab"
+Output: true
+Explanation: It is the substring "ab" twice.
+```
+
+---
+
+### [1] Code (23. 10. 08)
+
+*Retry*
+
+``` java
+// Runtime: 42 ms
+// Memory Usage: 44.2 MB
+// Ref : https://leetcode.com/submissions/detail/1067270115
+class Solution {
+    public boolean repeatedSubstringPattern(String s) {
+        int n = s.length();
+
+        for (int i = 1; i <= n/2; i++) {
+            String key = s.substring(0, i);
+            // System.out.println("key : " + key);
+            if (check(n, s, i, key)) {
+                return true;
+            }
+        }
+        return false;
+    }
+
+    private boolean check(int n, String s, int i, String key) {
+         if (n % i != 0) {
+             return false;
+         }
+
+        for (int idx = i; idx + i <= n; ) {
+            String target = s.substring(idx, idx + i);
+            // System.out.println("target : " + target);
+            idx += i;
+            if (!key.equals(target)) {
+                return false;
+            }
+        }
+        return true;
+    }
+}
+```
+
+* 깔끔한 구현 능력을 필요로 했던 문제
+
+---
+
+## Reference
+
+* [459. Repeated Substring Pattern](https://leetcode.com/problems/repeated-substring-pattern)