摘要：
Description：Invert a binary tree. 4 / \ 2 7/ \ / \1 3 6 9to 4 / \ 7 2 / \ / \9 6 3 1递归invert就好了。/** * Definition for a binary tree ... 阅读全文
摘要：
Description： Given an array of integers and an integer k, find out whether there there are two distinct indices i and j in the array such that nums[i... 阅读全文