Repeated Substring

0459-Repeated-Substring-Pattern.py

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+'''
+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.)
+'''
+# Time Complexity: O(n)
+# Space Complexity: O(n)
+class Solution:
+    def repeatedSubstringPattern(self, s: str) -> bool:
+        i, j, l = 1, 0, len(s)
+        lookup = [0] * (l + 1)
+
+        while i < l:
+          if s[i] == s[j]:
+            i += 1
+            j += 1
+            lookup[i] = j
+          elif not j:
+            i += 1
+          else:
+            j = lookup[j]
+        return lookup[l] and not lookup[l] % (l - lookup[l])