package main
import (
"fmt"
)
// Computes product of array except self.
// nums = input slice
// returns a new slice containing the result
func productExceptSelf(nums []int) []int {
size := len(nums)
answer := make([]int, size)
// ---- Prefix products ----
// answer[i] gets the product of all elements before i
prefix := 1
for i := 0; i < size; i++ {
answer[i] = prefix // store prefix product
prefix *= nums[i] // update prefix
// Example for nums = {5,2,3,4}:
// prefix values: 1, 5, 10, 30
}
// ---- Suffix products ----
// Multiply each answer[i] by product of all elements after i
suffix := 1
for i := size - 1; i >= 0; i-- {
answer[i] *= suffix // combine prefix * suffix
suffix *= nums[i] // update suffix
// suffix values: 1, 4, 12, 24, 120
// final answer: 24, 60, 40, 30
// 24 (24*1) 60 (12*5) 40 (10*4) 30 (30*1)
}
return answer
}
func main() {
arr := []int{5, 2, 3, 4}
result := productExceptSelf(arr)
fmt.Print("Result: ")
for _, x := range result {
fmt.Print(x, " ")
}
}
/*
run:
Result: 24 60 40 30
*/
