Cee

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

Cee

public class Solution {
    public int numTrees(int n) {
        if (n == 0) return 1;
        if (n == 1) return 1;
        if (n == 2) return 2;
        int ret = 0;
        for (int i = 1; i <= n; i++){
            ret = ret + numTrees(i - 1) * numTrees(n - i);   
        }
        return ret;

Cee

public class Solution {
    public int maxProfit(int[] prices) {
        int ret = 0;
        int index = 0;
        while (index < prices.length){
            if (index + 1 < prices.length){
                if (prices[index] < prices[index + 1]){
                    ret += prices[index + 1] - prices[index];
                }
            }

Cee

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

Cee

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

Cee

public class Solution {
    public int singleNumber(int[] A) {
        int[] count = new int[32];
        int result = 0;
        for (int i = 0; i < 32; i++) {
            for (int j = 0; j < A.length; j++) {
                if (((A[j] >> i) & 1) == 1) {
                    count[i]++;
                }
            }

Cee

public class Solution {
    public String reverseWords(String s) {
        s = s.trim();     
        int n = s.length();
        String str = "";
        while(s.lastIndexOf(" ") != -1){          
            int index = s.lastIndexOf(" ");
            str = str + s.substring(index + 1, n) + " ";
            s = s.substring(0, index).trim();
            n = s.length();

Cee

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

Cee

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

Cee

public class Solution {
    public int divide(int dividend, int divisor) {
        long a = dividend;
        long b = divisor;
        if (a == 0) return 0;
        boolean flag = (a > 0) ^ (b > 0);
        if (a < 0) a = -a;
        if (b < 0) b = -b;
        if (a < b) return 0;
        long ret = 0;