medium two pointers

16. 3Sum Closest

Leetcode Diary

Posted by Xudong on July 12, 2020

Given an array nums of n integers 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).

Thoughts

Same solution like 3 Sum
Store a closet var to compare and get the closet value

Code(JAVA)

public int threeSumClosest(int[] nums, int target) {
    int res = Integer.MAX_VALUE;
    Arrays.sort(nums);
    for(int i = 0; i < nums.length - 2; i++){
        int l = i +1, r = nums.length - 1;
        while(l < r) {
            int val = nums[i] + nums[l] + nums[r];
            if(res == Integer.MAX_VALUE || 
               Math.abs(target - val) < Math.abs(target - res))
                res = val;
            if(val == target)
                return val;
            else if(val < target)
                l ++;
            else
                r --;
        }
    }
    return res;
}