package main

import "fmt"

func main() {

	fmt.Println(productExceptSelf([]int{1, 2, 3, 4}))
}

func productExceptSelf(nums []int) []int {
	before := make([]int, len(nums))
	after := make([]int, len(nums))
	result := make([]int, len(nums))
	value1 := 1
	value2 := 1
	for i := 0; i < len(nums); i++ {

		if i == 0 {
			before[i] = 0
			continue
		}

		//fmt.Println("value:", value1)
		value1 = nums[i-1] * value1
		//fmt.Println("nums[i-1]:", nums[i-1])

		before[i] = value1
	}
	for i := len(nums) - 1; i >= 0; i-- {
		//fmt.Println("循环到:", nums[i])
		if i == len(nums)-1 {
			after[i] = 0
			continue
		}
		value2 *= nums[i+1]
		after[i] = value2
	}
	for i := 0; i < len(nums); i++ {
		if i == 0 {
			result[i] = after[i]
			continue
		}
		if i == len(nums)-1 {
			result[i] = before[i]
			continue
		}
		result[i] = before[i] * after[i]
	}
	//fmt.Println(before)
	//fmt.Println(after)
	return result
}