16. 3Sum Closest.md

16. 3Sum Closest

Problem

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).

tag:

Solution

java

    public int threeSumClosest(int[] nums, int target) {
        int closest = nums[0]+nums[1]+nums[nums.length-1];
        Arrays.sort(nums);
        for(int i=0; i<nums.length; i++) {
            int l = i+1, r = nums.length-1;
            while(l<r) {
                int sum = nums[i]+nums[l]+nums[r];
                if(sum==target) return sum;
                else if(sum<target) l++;
                else r--;
                closest = Math.abs(sum-target)<Math.abs(closest-target) ? sum : closest;
            }
        }
        return closest;
    }

go

func threeSumclosest(nums []int, target int) int {
	len := len(nums)
	close := nums[0] + nums[1] + nums[len-1]
	sort.Ints(nums)
	for i := 0; i < len; i++ {
		for p, q := i+1, len-1; p < q; {
			sum := nums[i] + nums[p] + nums[q]
			if sum == target {
				return sum
			} else if sum < target {
				p++
			} else {
				q--
			}
			if math.Abs(float64(sum-target)) < math.Abs(float64(close-target)) {
				close = sum
			}
		}
	}
	return close
}