Given an array S of n integers, find three integers in S such that the sum is closest to a given number, target. Return the sum of the three integers. You may assume that each input would have exactly one solution.
Example:
For example, given array S = {-1 2 1 -4}, and target = 1.
The sum that is closest to the target is 2. (-1 + 2 + 1 = 2).
Solution
This problem is identical to 3Sum. The difference being, instead of returning all sums, we return the (first) closest sum to the target. This simplification results in maintaining a solution with minimum distance to the target, mind in the code below, instead of checking for equivalence with the target and storing in a list.
Time complexity: $O(n^2)$
Space complexity: $O(1)$
Runtime: 18 ms (96.18%)