You are given an integer array nums and you have to return a new counts array. The counts array has the property where counts[i] is the number of smaller elements to the right of nums[i].
Example:
Given nums = [5, 2, 6, 1]
To the right of 5 there are 2 smaller elements (2 and 1).
To the right of 2 there is only 1 smaller element (1).
To the right of 6 there is 1 smaller element (1).
To the right of 1 there is 0 smaller element.
Return the array [2, 1, 1, 0].
Solution1：
思路：
https://discuss.leetcode.com/topic/31173/my-simple-ac-java-binary-search-code
Time Complexity: O(NlogN) Space Complexity: O(N)
Solution2：
思路：
Time Complexity: O(N) Space Complexity: O(N)
Solution Code：
