{ "data": { "question": { "questionId": "493", "questionFrontendId": "493", "boundTopicId": null, "title": "Reverse Pairs", "titleSlug": "reverse-pairs", "content": "

Given an integer array nums, return the number of reverse pairs in the array.

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A reverse pair is a pair (i, j) where:

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Example 1:

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\nInput: nums = [1,3,2,3,1]\nOutput: 2\nExplanation: The reverse pairs are:\n(1, 4) --> nums[1] = 3, nums[4] = 1, 3 > 2 * 1\n(3, 4) --> nums[3] = 3, nums[4] = 1, 3 > 2 * 1\n
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Example 2:

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\nInput: nums = [2,4,3,5,1]\nOutput: 3\nExplanation: The reverse pairs are:\n(1, 4) --> nums[1] = 4, nums[4] = 1, 4 > 2 * 1\n(2, 4) --> nums[2] = 3, nums[4] = 1, 3 > 2 * 1\n(3, 4) --> nums[3] = 5, nums[4] = 1, 5 > 2 * 1\n
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Constraints:

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Most standard library headers are already included automatically for your convenience.

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