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"]
]

典型的backtracking题目。需要一个函数来判断是否为回文序列，然后s从头至尾，如果前面的是回文序列，则recursive到s的后半部分。

 public IList<IList<string>> Partition(string s) {
        var res  = new  List<IList<string>>();
        if(s =="") return res;
        Backtracking(s,res,new List<string>());
        return res;
        
    }
    
    private void Backtracking(string s, List<IList<string>> res , List<string> cur)
    {
        if(s == "")
        {
            res.Add(new List<string>(cur));
        }
        else
        {
            for(int i =1;i<= s.Length;i++)
            {
                if(IsPalindrome(s.Substring(0,i))) 
                {
                    cur.Add(s.Substring(0,i));
                    Backtracking(s.Substring(i),res,cur);
                    cur. RemoveAt(cur.Count()-1);
                }
            }
        }
    }
    
    private bool IsPalindrome(string s)
    {
        if(s == null) return false;
        var c = s.ToCharArray();
        Array.Reverse(c);
        return s == new string(c);
    }