数组洗牌是指将一个数组中的元素顺序打乱，随机重新排列。
算法实现思路如下：
按照下标从大到小的顺序遍历数组，记下标为i 遍历时生成范围[0, i]的随机数j，交换下标i与下标j的数组元素
参考：java.util.Collections类中的shuffle方法
public static void shuffle(int[] nums) {
Random rnd = new Random();
for (int i = nums.length - 1; i > 0; i--) {
int j ...
LeetCode 331. Verify Preorder Serialization of a Binary Tree
One way to serialize a binary tree is to use pre-oder traversal. When we encounter a non-null node, we record the node's value. If it is a null node, we ...
Given a sorted positive integer array nums and an integer n, add/patch elements to the array such that any number in range [1, n] inclusive can be formed by the sum of some elements ...
Implement atoi to convert a string to an integer.
Hint: Carefully consider all possible input cases. If you want a challenge, please do not see below and ask yourself what are the possible input cases.
Notes: It is intended ...
使用Eclipse的正则表达式（Regular expressions）查找替换（Find/Replace）功能时，如果需要匹配多行，可以在搜索表达式中添加(?s)参数。
例如从下面的HTML文本中匹配<p class="strong"></p>的段落内容
可以采用正则表达式：(?s)<p class="strong">.*?</p>
<!doctype html>
<html>
<head>
<title>Example Domain</title>
<meta charset="utf-8" />
<style type="text/css ...