problem493

README

< Previous 　　　　　　　　　　　　　　　　 Next >

493. Reverse Pairs (Hard)

Given an array nums, we call (i, j) an important reverse pair if i < j and nums[i] > 2*nums[j].

You need to return the number of important reverse pairs in the given array.

Example1:

Input: [1,3,2,3,1]
Output: 2

Example2:

Input: [2,4,3,5,1]
Output: 3

Note:

1. The length of the given array will not exceed 50,000.
2. All the numbers in the input array are in the range of 32-bit integer.

Related Topics

[Sort] [Binary Indexed Tree] [Segment Tree] [Binary Search] [Divide and Conquer]

Similar Questions

1. Count of Smaller Numbers After Self (Hard)
2. Count of Range Sum (Hard)