3 Sum Closest

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.

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

class Solution(object):
    def threeSumClosest(self, nums, target):
        """
        :type nums: List[int]
        :type target: int
        :rtype: int
        """
        nums.sort()
        result = nums[0] + nums[1] + nums[2]
        for i in range(len(nums) - 2):
            l, r = i + 1, len(nums) - 1
            while l < r:
                s = nums[i] + nums[l] + nums[r]
                if s == target:
                    return s

                if abs(s - target) < abs(result - target):
                    result = s

                if s < target:
                    l += 1
                elif s > target:
                    r -= 1
        return result