p41.wax

(@include math)

(func isPrime (param n int) (result int)
	(for i 2 (<= i (cast (call sqrt n) int)) 1 (do
		(if (= (% n i) 0) (then
			(return 0)
		))
	))
	(return 1)
)

(func permute (param max int) (param digits int) (param n int) (result int)
	(if (= digits 0) (then
		; Digit permutation is complete; test for primality
		(if (call isPrime n) (then
			(return n)
		)(else
			(return 0))
		)
	)(else
		; Return the max of all children (permutations that are prime)
		(let best int 0)
		(for i 1 (<= i max) 1 (do
			(let b int (<< 1 (- i 1)))
			(if (& b digits) (then
				(let r int (call permute max (^ digits b) (+ i (* n 10))))
				(if (> r best) (then
					(set best r)
				))
			))
		))
		(return best)
	))
)

(func findPrimeNPandigital (param max int) (result int)
	(let b int 0)
	(for i 1 (<= i max) 1 (do
		(set b (| b (<< 1 (- i 1))))
	))
	
	(return (call permute max b 0))
)

(func main (result int)
	; First try 9 digits, then 8, ...
	(let digitCount int 9)
	(let solution int 0)
	(while (= solution 0) (do
		(set solution (call findPrimeNPandigital digitCount))
		(set digitCount (- digitCount 1))
	))
	(print solution)
	(return 0)
)