Algoexpert Solutions

three_number_sum.go

package main

// [12, 3, 1]
// array distinct, solutions 3 numbers group must be unique
// [3,1,2]
// [1,2,-6]
import ("fmt"
				"sort")
func ThreeNumberSum(array []int, target int) [][]int {
	solutions := make([][]int,0)
	
	
	
	// must be sorted
	sort.Ints(array)
	
	for i:=0; i < len(array); i++ {
		leftIndex := i + 1 // set left pointer as currentIndex + 1
		rightIndex := len(array) - 1 // right pointer as the end of the array
		
		for leftIndex < rightIndex { // continues loop the pointer shifter until the leftIndex pointer passed over rightIndex
			currentSum := array[i] + array[leftIndex] + array[rightIndex] // current sum to test all the three sum values
			if currentSum > target { // if the currentsum is more than the target 
				 // we need to lower down the value by shifting the right index - 1
				rightIndex -= 1
			} else if currentSum < target {
				// if the currentsum is less than the target 
				 // we need to increase the value by shifting the left index + 1
				leftIndex += 1
			} else if currentSum == target {
				// if we found the currentsum match the target sum, appennd the solution
				solutions = append(solutions, []int{ array[i], array[leftIndex], array[rightIndex]})
				// then move forward leftIndex, and move the rightIndex backward
				leftIndex +=1 
				rightIndex -=1
			}
		}
	}
	
	fmt.Println(solutions)
	
	return solutions


}