b27lu

public class Solution {
    ArrayList<String> wordBreak(String s, Set<String> dict) {
        int length = s.length();
        
        //create the word ending character's index list for each character
        ArrayList<ArrayList<Integer>> record = new ArrayList<ArrayList<Integer>>(length);
        for(int i = 0;i<length;i++)
            record.add(new ArrayList<Integer>());

        //each character can be the ending character of some word

b27lu

public class Solution {
    public boolean wordBreak(String s, Set<String> dict) {
        if(s == null || s.length() == 0 || dict == null)
            return true;
            
        int length = s.length();

        //dp[i] is true when the substring from i to the end can be partitioned
        boolean[] dp = new boolean[length+1];
        for(boolean b : dp)

b27lu

public class Solution {
    public int firstMissingPositive(int[] A) {
        int n = A.length;

        int i = 0;
        while(i<n){
            if(A[i] > 0 && A[i] <= n && A[i]-1 != i && A[A[i]-1] != A[i]){
                int temp = A[A[i]-1];
                A[A[i]-1] = A[i];
                A[i] = temp;

b27lu

public class Solution {
    public String reverseWords(String s) {
        if(s == null)
            return s;
        
        //trim leading and trailing spaces    
        String trimmed = s.trim();
        
        //split string using space(s) as delimiter
        String[] splitted = trimmed.split("\\s+");

b27lu

/**
 * Definition for singly-linked list.
 * class ListNode {
 *     int val;
 *     ListNode next;
 *     ListNode(int x) {
 *         val = x;
 *         next = null;
 *     }
 * }

b27lu

/**
 * Definition for singly-linked list with a random pointer.
 * class RandomListNode {
 *     int label;
 *     RandomListNode next, random;
 *     RandomListNode(int x) { this.label = x; }
 * };
 */
public class Solution {
    public RandomListNode copyRandomList(RandomListNode head) {

b27lu

/**
 * Definition for singly-linked list with a random pointer.
 * class RandomListNode {
 *     int label;
 *     RandomListNode next, random;
 *     RandomListNode(int x) { this.label = x; }
 * };
 */
public class Solution {
    public RandomListNode copyRandomList(RandomListNode head) {

b27lu

/**
 * Definition for singly-linked list.
 * public class ListNode {
 *     int val;
 *     ListNode next;
 *     ListNode(int x) {
 *         val = x;
 *         next = null;
 *     }
 * }

b27lu

/**
 * Definition for binary tree
 * public class TreeNode {
 *     int val;
 *     TreeNode left;
 *     TreeNode right;
 *     TreeNode(int x) { val = x; }
 * }
 */
public class Solution {

b27lu

/**
 * Definition for binary tree
 * public class TreeNode {
 *     int val;
 *     TreeNode left;
 *     TreeNode right;
 *     TreeNode(int x) { val = x; }
 * }
 */
public class Solution {