16. 3Sum Closest

Stanislav Gumeniuk included in Leetcode Leetcode-Problem

2020-06-01 168 words One minute

Contents

Problem

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).

Constraints

3 <= len(nums) <= 10^3
-10^3 <= nums[i] <= 10^3
-10^4 <= target <= 10^4

Solution

Brute force

func threeSumClosest(nums []int, target int) int {
    a:= make(map[int]int,0)
    
    for idx:=range nums {
        a[nums[idx]]++
    }
    
    closest := math.MaxInt32
    ressum := target

    for idx := range a {
        a[idx]--
        for jdx:= range a {
            if a[jdx] <= 0 {
                continue
            }
            a[jdx]--
            
            for kdx := range a {
                if a[kdx] <= 0 {
                    continue
                }
                
                sum := idx+jdx+kdx
                if int(math.Abs(float64(target-sum))) < closest {
                    ressum = sum
                    closest = int(math.Abs(float64(target-sum)))
                }
            }
                        
            a[jdx]++
        }
        a[idx]++
    }
    
    return ressum
}