Product of every element except itself

def product_except_self(nums):
    n = len(nums)
    out = [1] * n
    left = 1
    for i in range(n):              # out[i] = product of everything left of i
        out[i] = left
        left *= nums[i]
    right = 1
    for i in range(n - 1, -1, -1):  # multiply in everything right of i
        out[i] *= right
        right *= nums[i]
    return out

#include <vector>
using namespace std;

vector<int> solve(vector<int> nums) {
    int n = nums.size();
    vector<int> out(n, 1);
    int left = 1;
    for (int i = 0; i < n; i++) {        // out[i] = product of everything left of i
        out[i] = left;
        left *= nums[i];
    }
    int right = 1;
    for (int i = n - 1; i >= 0; i--) {   // multiply in everything right of i
        out[i] *= right;
        right *= nums[i];
    }
    return out;
}

class Solution {
    public int[] productExceptSelf(int[] nums) {
        int n = nums.length;
        int[] out = new int[n];
        int left = 1;
        for (int i = 0; i < n; i++) {        // out[i] = product of everything left of i
            out[i] = left;
            left *= nums[i];
        }
        int right = 1;
        for (int i = n - 1; i >= 0; i--) {   // multiply in everything right of i
            out[i] *= right;
            right *= nums[i];
        }
        return out;
    }
}

function productExceptSelf(nums) {
  const n = nums.length, out = new Array(n).fill(1);
  let left = 1;
  for (let i = 0; i < n; i++) {        // out[i] = product of everything left of i
    out[i] = left;
    left *= nums[i];
  }
  let right = 1;
  for (let i = n - 1; i >= 0; i--) {   // multiply in everything right of i
    out[i] *= right;
    right *= nums[i];
  }
  return out;
}

fn solve(nums: &[i32]) -> Vec<i32> {
    let n = nums.len();
    let mut out = vec![1; n];
    let mut left = 1;
    for i in 0..n {                 // out[i] = product of everything left of i
        out[i] = left;
        left *= nums[i];
    }
    let mut right = 1;
    for i in (0..n).rev() {         // multiply in everything right of i
        out[i] *= right;
        right *= nums[i];
    }
    out
}

-- scanl gives the products to the left of each slot, scanr those to the right.
solve :: [Int] -> [Int]
solve xs = zipWith (*) (init (scanl (*) 1 xs)) (tail (scanr (*) 1 xs))