LeetCode 131: Palindrome Partitioning

Given a string s, partition s such that every substring of the partition is a palindrome.
Return all possible palindrome partitioning of s.
For example, given s = "aab",
Return

  [
    ["aa","b"],
    ["a","a","b"]
  ]

public class Solution {
    private List<List<String>> result;
    private List<String> ret;
    
    public List<List<String>> partition(String s) {
        // Backtracking problem
        result = new LinkedList<>();
        int n = s.length();
        
        if (n == 0)
            return result;
            
        ret = new LinkedList<>();
        
        backTracking(s, 0);
        
        return result;
    }
    
    private void backTracking(String s, int cnt)
    {
        if (cnt == s.length())
        {
            // Note: We should allocate new memory for ret because it is changable.
            List<String> retCopy = new LinkedList<>(ret);
            result.add(retCopy);
            return;
        }
        else
        {
            for (int i = cnt; i < s.length(); i++)
            {
                String str = s.substring(cnt, i+1);
                
                if (place(str))
                {
                    ret.add(str);
                    backTracking(s, i+1);
                    ret.remove(ret.size()-1);
                }
            }
        }
    }
    
    // Verify if it is palindrome string or not
    private boolean place(String s)
    {
        // Note: Single character is also palindrome string
        int n = s.length();
        
        for (int i = 0; i < n/2; i++)
            if (s.charAt(i) != s.charAt(n-i-1))
                return false;
                
        return true;
    }
}