How to find the product of all elements of an array modulo 10^9+7 ?

[radha gogia]

I have written below code ,for the problem stated on below link under topic Array multiplication , I am unable to get the insight of why is the code not working for any test case ?

https://www.hackerearth.com/practice/math/number-theory/modulus-arithmetic/tutorial/

#include <stdio.h>
#include<inttypes.h>
#include<stdint.h>
#include<math.h>
 
int main()
{
uintmax_t size;
uintmax_t product=1;
scanf(" %ju",&size);
uintmax_t i;
if(size<=10000 && size>=1)
{
 
uintmax_t array[size];;
for(i=0;i<size;i++)
{
 
scanf(" %ju",&array[i]);
product=product*array[i];
 
}
 
uintmax_t a=pow(10,9);
uintmax_t b=a+7;
uintmax_t c=product % b;
printf("%ju",c);
}
 
  return 0;
}
 

[weaknessforcats]

It might be right here:

uintmax_t array[size];;

At the time this line of code is executed, size has not been initialized so you get whatever value is in the variable.

Also, static arrays like this need t know the size before the array can be created.

I suggest:

unitnmax_t* array = 0;

scanf your size

array = malloc(size * sizeof(unitmax_t));

then initialize the array elements

then plug in your element values