Pascal's Triangle Program

This is Pascal's triangle program. Was probably one of the hardest programs I had during my second year. But looking back, its not as hard as it seems. For those who have trouble with this program, I suggest you to write it down, step by step with pencil and paper to see how the program works. If you need help, feel free to ask.

#include<stdio.h>
main()
{
int d,i,j,n,a[50],k,b[50];
printf("enter limit");
scanf("%d",&n);
d=n;
for(i=0;i<n;i++)
{
a[0]=1;
a[i]=1;
for(j=1;j<i;j++)
{
a[j]=b[j-1]+b[j];
}
for(k=0;k<(d-1);k++)
{
printf(" ");
}
d--;
for(k=0;k<=i;k++)
{
printf("%d",a[k]);
printf(" ");
}
for(k=0;k<=i;k++)
printf("\n");
for(k=0;k<=i;k++)
b[k]=a[k];
}
}