int i, space, rows, k=0, count = 0, count1 = 0;
row=5;
for(i=1; i<=rows; ++i)
{
for(space=1; space <= rows-i; ++space)
{
printf(" ");
++count;
}
while(k != 2*i-1)
{
if (count <= rows-1)
{
printf("%d ", i+k);
++count;
}
else
{
++count1;
printf("%d ", (i+k-2*count1));
}
++k;
}
count1 = count = k = 0;
printf("\n");
}
Output
1
2 3 2
3 4 5 4 3
4 5 6 7 6 5 4
5 6 7 8 9 8 7 6 5