LeetCode 16. 3Sum Closest

Question

Given an integer array nums of length n and an integer target, find three integers in nums such that the sum is closest to target.

Return the sum of the three integers.

You may assume that each input would have exactly one solution.

Example 1:

Input: nums = [-1,2,1,-4], target = 1
Output: 2
Explanation: The sum that is closest to the target is 2. (-1 + 2 + 1 = 2).

Example 2:

Input: nums = [0,0,0], target = 1
Output: 0

Constraints:

• 3 <= nums.length <= 1000
• -1000 <= nums[i] <= 1000
• -104 <= target <= 104

Source: https://leetcode.com/problems/3sum-closest/

Solution

public int threeSumClosest(int[] nums, int target) {
    Arrays.sort(nums);
    int diff = Integer.MAX_VALUE;
    int closest = 0;
    for (int i = 0; i < nums.length - 2; i++) {
        int j = i + 1;
        int k = nums.length - 1;
        // two sum is a complete search for any approximations of target
        while (j < k) {
            int sum = nums[i] + nums[j] + nums[k];
            if (Math.abs(target - sum) < diff) {
                diff = Math.abs(target - sum);
                closest = sum;
            }
            if (sum < target) {
                j++;
            } else {
                k--;
            }
        }
    }
    return closest;
}