added product array puzzle

GFG/product_array.cpp

@@ -0,0 +1,74 @@
+// Question link is - https://practice.geeksforgeeks.org/problems/product-array-puzzle4525/1
+
+
+//Initial template for C++
+
+#include<bits/stdc++.h>
+using namespace std;
+
+
+
+ // } Driver Code Ends
+//User function template for C++
+
+class Solution{
+  public:
+    // nums: given vector
+    // return the Product vector P that hold product except self at each index
+    vector<long long int> productExceptSelf(vector<long long int>& nums, int n) {
+       long long int pro=1,zero=0;
+       for(int i=0;i<n;i++)
+       {  if(nums[i]!=0)
+            pro*=nums[i];
+          else
+           zero++;
+       }
+       if(zero>1)
+        pro=zero;
+        vector <long long int> ans;
+        for(int i=0;i<n;i++)
+       {  
+          if(zero>0)
+          {
+              if(nums[i]==0 && zero==1)
+                ans.push_back(pro);
+              else 
+                ans.push_back(0);
+          }
+          else
+          {
+              long long int x=pro/nums[i];
+              ans.push_back(x);
+          }
+       }
+       return ans;
+    }
+};
+
+
+// { Driver Code Starts.
+int main()
+ {
+    int t;  // number of test cases
+    cin>>t;
+    while(t--)
+    {
+        int n;  // size of the array
+        cin>>n;
+        vector<long long int> arr(n),vec(n);
+
+        for(int i=0;i<n;i++)    // input the array
+        {
+            cin>>arr[i];
+        }
+        Solution obj;
+        vec = obj.productExceptSelf(arr,n);   // function call
+
+        for(int i=0;i<n;i++)    // print the output
+        {
+            cout << vec[i] << " ";
+        }
+        cout<<endl;
+    }
+	return 0;
+}  // } Driver Code Ends