array_product_except_ith_element.cpp

/*
Given an array A of size N, construct a Product Array P (of same size) such that P is equal to the product of all the elements of A except A[i].

Input:
The first line of input contains an integer T denoting the number of test cases. T testcases follow. Each testcase contains two lines of input. The first line is N. The second line contains N elements separated by spaces.

Output:
For each testcase, print the Product array P.

Constraints:
1 <= T <= 10
1 <= N <= 1000
1 <= Ai <= 20

Example:
Input:
2
5
10 3 5 6 2
2
12 20
Output:
180 600 360 300 900
20 12

Explanation:
Testcase1: For the product array P, at i=0 we have 3*5*6*2. At i=1 10*5*6*2. At i=2 we have 10*3*6*2. At i=3 we have 10*3*5*2. At i=4 we have 10*3*5*6
So P is 180 600 360 300 900
*/





#include<bits/stdc++.h>
using namespace std;

int main(){
    ios_base::sync_with_stdio(false);
    cin.tie(NULL);
    cout.tie(NULL);
    int t;
    cin>>t;
    while(t--){
        int n;
        cin>>n;
        int a[n];
        for(int i=0;i<n;i++) cin>>a[i];
        int left[n], right[n], res[n];
        int prod=1;
        left[0]=1;
        right[n-1]=1;

        for(int i=1;i<n;i++)
            left[i]=a[i-1]*left[i-1];

        for(int i=n-2;i>=0;i--)
            right[i]=a[i+1]*right[i+1];

        res[0]=right[0];
        res[n-1]=left[n-1];
        for(int i=1;i<n-1;i++)
            res[i]=left[i]*right[i];

        for(int i=0;i<n;i++)
         cout<<res[i]<<" ";
         cout<<endl;
    }

return 0;
}