daifu

/*
Suppose a sorted array is rotated at some pivot unknown to you beforehand.

(i.e., 0 1 2 4 5 6 7 might become 4 5 6 7 0 1 2).

You are given a target value to search. If found in the array return its index, otherwise return -1.

You may assume no duplicate exists in the array.

Algorithm:

daifu

/*
Suppose a sorted array is rotated at some pivot unknown to you beforehand.

(i.e., 0 1 2 4 5 6 7 might become 4 5 6 7 0 1 2).

You are given a target value to search. If found in the array return its index, otherwise return -1.

You may assume no duplicate exists in the array.

Algorithm:

daifu

/*
Given a number represented as an array of digits, plus one to the number.
*/
public class Solution {
    public int[] plusOne(int[] digits) {
        // Start typing your Java solution below
        // DO NOT write main() function
        int len = digits.length - 1;
        digits[len] = digits[len] + 1;
        int carry = digits[len] >= 10 ? 1 : 0;

daifu

/*
Merged two sorted array. 

merged B into A
*/

public class Solution {
    public void merge(int A[], int m, int B[], int n) {
        // Start typing your Java solution below
        // DO NOT write main() function

daifu

/*
Given two binary trees, write a function to check if they are equal or not.

Two binary trees are considered equal if they are structurally identical and the nodes have the same value.

Algorithm:
1. It is a recursive function that check p.left and q.left,
and p.right and p.right, and p.val and q.val
*/

daifu

/*
Given inorder and postorder traversal of a tree, construct the binary tree.

Note:
You may assume that duplicates do not exist in the tree.
*/
/**
 * Definition for binary tree
 * public class TreeNode {
 *     int val;

daifu

/*
Given a binary tree, check whether it is a mirror of itself (ie, symmetric around its center).

For example, this binary tree is symmetric:

    1
   / \
  2   2
 / \ / \
3  4 4  3

daifu

/*
Given a binary tree, return the level order traversal of its nodes' values. (ie, from left to right, level by level).

For example:
Given binary tree {3,9,20,#,#,15,7},

    3
   / \
  9  20
    /  \

daifu

/*
Given a collection of integers that might contain duplicates, S, return all possible subsets.

Note:

Elements in a subset must be in non-descending order.
The solution set must not contain duplicate subsets.
For example,
If S = [1,2,2], a solution is:

daifu

static class Wrapper {
  TreeNode node;
  int level;
  Wrapper(TreeNode node, int level) {
    this.node = node;
    this.level = level;
  }
}

static int skip;