class Solution { public int solution(int n, String str) { int count = 0; for (int i = 0; i < str.length(); i++) { for(int j = i;j<str.length();j++){ String substring = str.substring(i, j + 1); if(isDefineString(substring)){ count++; } } } return count; } public boolean isDefineString(String s){ if(s.length() < 4){ return false; } boolean ret = true; int n = (s.length() + 2) / 3; for(int i = 1;i <= n;i++){ char c1 = s.charAt(i - 1); char c2 = s.charAt(2 * n - i - 1); char c3 = s.charAt(2*n + i - 2 - 1); if( c1 == c2 && c2 == c3 && (s.length() + 2) % 3 == 0) { ret = true; }else{ return false; } } return ret; } }