{ "data": { "question": { "questionId": "2917", "questionFrontendId": "2824", "boundTopicId": null, "title": "Count Pairs Whose Sum is Less than Target", "titleSlug": "count-pairs-whose-sum-is-less-than-target", "content": "Given a 0-indexed integer array nums of length n and an integer target, return the number of pairs (i, j) where 0 <= i < j < n and nums[i] + nums[j] < target.\n

 

\n

Example 1:

\n\n
\nInput: nums = [-1,1,2,3,1], target = 2\nOutput: 3\nExplanation: There are 3 pairs of indices that satisfy the conditions in the statement:\n- (0, 1) since 0 < 1 and nums[0] + nums[1] = 0 < target\n- (0, 2) since 0 < 2 and nums[0] + nums[2] = 1 < target \n- (0, 4) since 0 < 4 and nums[0] + nums[4] = 0 < target\nNote that (0, 3) is not counted since nums[0] + nums[3] is not strictly less than the target.\n
\n\n

Example 2:

\n\n
\nInput: nums = [-6,2,5,-2,-7,-1,3], target = -2\nOutput: 10\nExplanation: There are 10 pairs of indices that satisfy the conditions in the statement:\n- (0, 1) since 0 < 1 and nums[0] + nums[1] = -4 < target\n- (0, 3) since 0 < 3 and nums[0] + nums[3] = -8 < target\n- (0, 4) since 0 < 4 and nums[0] + nums[4] = -13 < target\n- (0, 5) since 0 < 5 and nums[0] + nums[5] = -7 < target\n- (0, 6) since 0 < 6 and nums[0] + nums[6] = -3 < target\n- (1, 4) since 1 < 4 and nums[1] + nums[4] = -5 < target\n- (3, 4) since 3 < 4 and nums[3] + nums[4] = -9 < target\n- (3, 5) since 3 < 5 and nums[3] + nums[5] = -3 < target\n- (4, 5) since 4 < 5 and nums[4] + nums[5] = -8 < target\n- (4, 6) since 4 < 6 and nums[4] + nums[6] = -4 < target\n
\n\n

 

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Constraints:

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