Average sequence : HackerEarth Problem Solution

Today Oz is playing with two lists $A$ and $B$. List $A$ contains $N$ elements. List $B$ is formed by replacing every element of List $A$ by average value of all elements before current element including current one. 

For example :

If list $A$ is like : $a,b,c$ then

list $B$ will be like : $\frac{a}{1},\frac{a+b}{2},\frac{a+b+c}{3}$

Now you are given list $B$ and you have to find list $A$. So help Oz with this task.

Input :
First line contain an integer $N$ - size of list $B$
Second line contains $N$ space separated integers - elements of list $B$

Output :
Output $N$ space separated integers - elements of list $A$

Test data is such that list $A$ elements are always integers.

Constraints :
$1\le N\le 100$
$1\le valueofeachelement\le 10$ ^$9$ 

Implementation:

#include <stdio.h>
int main()
{
 int *a,*b;
 int n;
 int i,average,current = 1, j=0,sum=0,res;
 scanf("%d",&n);
 a=(int*)malloc(sizeof(int)*n);
 b=(int*)malloc(sizeof(int)*n);
 for(i=0;i<n;i++)
 {
  scanf("%d",(b+i));
  res=(*(b+i)*current)-sum;
  sum += res;
  current++;
  *(a+i) = res;
 }
 for(i=0;i<n;i++)
  printf("%d ",*(a+i));
 free(a);
 free(b);
 return 0;