16. 3Sum Closest

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LeetCode

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Problem

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 <= 500
• -1000 <= nums[i] <= 1000
• $-10^4 <= target <= 10^4$

Code

class Solution {
    public int threeSumClosest(int[] nums, int target) {
        Arrays.sort(nums);
        int diff = Integer.MAX_VALUE;
        int res = 0;
        for(int i = 0; i < nums.length - 2; i++){
            if(i != 0 && nums[i] == nums[i - 1]) continue;
            int left = i + 1;
            int right = nums.length - 1;

            while(left < right){
                int sum = nums[i] + nums[left] + nums[right];
                if(Math.abs(sum - target) < diff){
                    diff = Math.abs(sum - target);
                    res = sum;
                }

                if(target == sum){
                    return sum;
                } else if(sum > target){
                    right--;
                } else if (sum < target){
                    left++;
                }
            }
        }

        return res;
    }
}