ThreeSumClosest.java

import java.util.Arrays;

/**
 * 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.
 * <p>
 * For example, given array S = {-1 2 1 -4}, and target = 1.
 * <p>
 * The sum that is closest to the target is 2. (-1 + 2 + 1 = 2).
 * <p>
 * Accepted.
 */
public class ThreeSumClosest {

    public int threeSumClosest(int[] nums, int target) {
        Arrays.sort(nums);

        int result = nums[0] + nums[1] + nums[2];
        for (int i = 0; i < nums.length - 2; i++) {
            int l = i + 1, r = nums.length - 1;
            while (l < r) {
                int tmp = nums[i] + nums[l] + nums[r];
                if (tmp == target) {
                    return tmp;
                }
                if (Math.abs(tmp - target) < Math.abs(result - target)) {
                    result = tmp;
                }
                if (tmp < target) {
                    l++;
                } else if (tmp > target) {
                    r--;
                }
            }
        }

        return result;
    }

}