高频题（0）
1. Symmetric Tree
Given the root of a binary tree, check whether it is a mirror of itself (i.e., symmetric around its center).
2. 判断点是否在长方形内
如何check一个点在一个长方形内，给提供长方形四个点坐标
3. 去掉奇数
给一个数组，一堆整数，将奇数都去掉，例如[1,2,3,4,8]->[2,4,8]
4. Reverse Linked List
Given the head of a singly linked list, reverse the list, and return the reversed list.
5. Most Profit Assigning Work
You have n jobs and m workers. You are given three arrays: difficulty, profit, and worker where:
difficulty[i] and profit[i] are the difficulty and the profit of the ith job, and
worker[j] is the ability of jth worker (i.e., the jth worker can only complete a job with difficulty at most worker[j]).
Every worker can be assigned at most one job, but one job can be completed multiple times.
For example, if three workers attempt the same job that pays $1, then the total profit will be $3. If a worker cannot complete any job, their profit is $0.
Return the maximum profit we can achieve after assigning the workers to the jobs.
