档案日期2016的5

题目描述：

LeetCode 332. Reconstruct Itinerary

Given a list of airline tickets represented by pairs of departure and arrival airports [from, to], reconstruct the itinerary in order. All of the tickets belong to a man who departs from JFK. ...

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

Java代码：

public static void shuffle(int[] nums) {
    Random rnd = new Random();
    for (int i = nums.length - 1; i > 0; i--) {
        int j = rnd.nextInt(i + 1); ...

题目描述：

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 ...