PalindromePartitioning.java

/*
 Author:     Andy, nkuwjg@gmail.com
 Date:       Jan 20, 2015
 Problem:    Palindrome Partitioning
 Difficulty: Easy
 Source:     https://oj.leetcode.com/problems/palindrome-partitioning/
 Notes:
 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"]
 ]

 Solution: ...
 */

public class Solution {
    public List<List<String>> partition(String s) {
        List<List<String>> res = new ArrayList<List<String>>();
        int n = s.length();
        boolean[][] dp = new boolean[n][n];
        for (int i = n - 1; i >= 0; --i) {
            for (int j = i; j < n; ++j) {
                dp[i][j]=(s.charAt(i)==s.charAt(j))&&(j<i+2||dp[i+1][j-1]);
            }
        }
        ArrayList<String> path = new ArrayList<String>();
        dfs(s, dp, 0, path, res);
        return res;
    }
    public void dfs(String s, boolean[][] dp, int start, ArrayList<String> path, List<List<String>> res) {
        if (s.length() == start) {
            res.add(new ArrayList<String>(path));
            return;
        }
        for (int i = start; i < s.length(); ++i) {
            if (dp[start][i] == false) continue;
            path.add(s.substring(start,i+1));
            dfs(s, dp, i+1,path,res);
            path.remove(path.size()-1);
        }
    }
}