Bash printing diagonal of any size array

Question

So here I have the following code:

#!/bin/bash
awk \'BEGIN {f=4} {printf($f\" \"); f=f-1}\'

Which will take input such as:

Answer 1

The problem is, NF at BEGIN section is not the number of tokens on the first line. The following works:

awk '{if (!f) f = NF; printf($f" "); f=f-1}'

Edit: as per suggestions in the comments, a cleaner and safer way is:

awk '{if (!f) f = NF; printf("%s ", $f); f--}'