Watch 10 video solutions for Count Pairs Whose Sum is Less than Target, a easy level problem involving Array, Two Pointers, Binary Search. This walkthrough by NeetCodeIO has 15,313 views views. Want to try solving it yourself? Practice on FleetCode or read the detailed text solution.
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.
Example 1:
Input: nums = [-1,1,2,3,1], target = 2 Output: 3 Explanation: There are 3 pairs of indices that satisfy the conditions in the statement: - (0, 1) since 0 < 1 and nums[0] + nums[1] = 0 < target - (0, 2) since 0 < 2 and nums[0] + nums[2] = 1 < target - (0, 4) since 0 < 4 and nums[0] + nums[4] = 0 < target Note that (0, 3) is not counted since nums[0] + nums[3] is not strictly less than the target.
Example 2:
Input: nums = [-6,2,5,-2,-7,-1,3], target = -2 Output: 10 Explanation: There are 10 pairs of indices that satisfy the conditions in the statement: - (0, 1) since 0 < 1 and nums[0] + nums[1] = -4 < target - (0, 3) since 0 < 3 and nums[0] + nums[3] = -8 < target - (0, 4) since 0 < 4 and nums[0] + nums[4] = -13 < target - (0, 5) since 0 < 5 and nums[0] + nums[5] = -7 < target - (0, 6) since 0 < 6 and nums[0] + nums[6] = -3 < target - (1, 4) since 1 < 4 and nums[1] + nums[4] = -5 < target - (3, 4) since 3 < 4 and nums[3] + nums[4] = -9 < target - (3, 5) since 3 < 5 and nums[3] + nums[5] = -3 < target - (4, 5) since 4 < 5 and nums[4] + nums[5] = -8 < target - (4, 6) since 4 < 6 and nums[4] + nums[6] = -4 < target
Constraints:
1 <= nums.length == n <= 50-50 <= nums[i], target <= 50