Palindrome Partitioning
/**
* Given a string s, partition s such that every substring of the partition is a palindrome.
* Return the minimum cuts needed for a palindrome partitioning of s.
* For example, given s = "aab",
* Return 1 since the palindrome partitioning ["aa","b"] could be produced using 1 cut.
*/
public class Solution {
public int minCut(String s) {
int len = s.length();
int[] dp = new int[len + 1];
boolean[][] isPa = new boolean[len][len];
for(int i = 0; i <= len; i++){
dp[i] = len - i;
}
for(int i = 0; i < len; i++){
isPa[i][i] = true;
}
for(int i = len - 1; i >= 0; i--){
for(int j = i; j < len; j++){
if((s.charAt(i) == s.charAt(j)) && ( j - i < 2 || isPa[i + 1][j - 1])){
isPa[i][j] = true;
dp[i] = Math.min(dp[i], dp[j + 1] + 1);
}
}
}
return dp[0] - 1;
}
}
/**
* 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 {
public ArrayList<ArrayList<String>> partition(String s) {
ArrayList<ArrayList<String>> res = new ArrayList<ArrayList<String>>();
if(s == null || s.length() == 0)
return res;
boolean[][] isPa = new boolean[s.length()][s.length()];
// single-char word is a palindrome.
for(int i = 0; i < s.length(); i++){
isPa[i][i] = true;
}
for(int i = s.length() - 1; i >= 0; i--){
for(int j = i; j < s.length(); j++){
if((s.charAt(i) == s.charAt(j)) && ( j - i < 2 || isPa[i + 1][j - 1])){
isPa[i][j] = true;
}
}
return partitionHelper(s, 0, isPa);
}
public ArrayList<ArrayList<String>> partitionHelper(String s, int start, boolean[][] isPa){
ArrayList<ArrayList<String>> pa = new ArrayList<ArrayList<String>>();
if(s.length() == start){
// backtracking start
pa.add(new ArrayList<String>());
return pa;
}
for(int i = start; i < s.length(); i++){
if(isPa[start][i]){
for(ArrayList<String> subPa : partitionHelper(s, i + 1, isPa)){
subPa.add(0, s.substring(start, i + 1));
pa.add(subPa);
}
}
}
return pa;
}
}