Product of Array Except Self

Problem statement

Build an output array where index i holds the product of every value in nums except nums[i]. Aim for linear time and avoid dividing by nums[i].

Example:

Input:

[1, 2, 3, 4]

Expected output:

[24, 12, 8, 6]

Practice on LeetCode: Product of Array Except Self

Golang Solution

func productExceptSelf(nums []int) []int {
    
    n := len(nums)
    left := make([]int, n)
    right := make([]int, n)
    answer := make([]int, n)

    left[0] = 1
    left[1] = nums[0]
    
    i := 2
    for i < n {
        left[i] = left[i-1] * nums[i-1]
        i += 1
    }

    right[n-1] = 1
    right[n-2] = nums[n-1]

    j := n-3
    for j >= 0 {
        right[j] = right[j+1] * nums[j+1]
        j -= 1
    }

    for i := 0; i < n; i++ {
        answer[i] = left[i] * right[i]
    }

    return answer
}