3 Sum Closest

3 Sum Closest

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Accepted

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.

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Yes

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).

Note

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

Challenge

O(n^2) time, O(1) extra space

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public class Solution {
    /**
     * @param numbers: Give an array numbers of n integer
     * @param target : An integer
     * @return : return the sum of the three integers, the sum closest target.
     */
    public int threeSumClosest(int[] numbers ,int target) {
        // write your code here
        if(numbers == null || numbers.length <= 2) return 0;
        long closest = (long) Integer.MAX_VALUE;
        Arrays.sort(numbers);
        for(int i = 0; i < numbers.length - 2; i++){
         
            int j = i + 1, k = numbers.length - 1;
            while(j < k){
               
                int sum = numbers[i] + numbers[j] + numbers[k];
                if(numbers[i] + numbers[j] + numbers[k] == target){
                    return target;
                } else if(numbers[i] + numbers[j] + numbers[k] > target){
                    k--;
                } else j++;
               
                closest = Math.abs(sum - target) > Math.abs(closest - target) ? closest : sum;
               
            }
        }
        return (int) closest;
    }
}