459. Repeated Substring Pattern
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 1:
Input: s = "abab"
Output: true
Explanation: It is the substring "ab" twice.
Example 2:
Input: s = "aba"
Output: false
Example 3:
Input: s = "abcabcabcabc"
Output: true
Explanation: It is the substring "abc" four times or the substring "abcabc" twice.
Constraints:
- 1 <= s.length <= 104
- s consists of lowercase English letters.
public boolean repeatedSubstringPattern(String str) {
String s = str + str;
return s.substring(1, s.length() - 1).contains(str);
}public boolean repeatedSubstringPattern(String str) {
int l = str.length();
for(int i=l/2;i>=1;i--) {
if(l%i==0) {
int m = l/i;
String subS = str.substring(0,i);
StringBuilder sb = new StringBuilder();
for(int j=0;j<m;j++){
sb.append(subS);
}
if(sb.toString().equals(str)){
return true;
}
}
}
return false;
}