Submission #172537

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Source Code Expand

(define N (read))

(define (readnums N)
  (define (readnums-r l i)
    (if (< 0 i)
        (readnums-r (cons (read) l) (- i 1))
        l))
  (readnums-r '() N))

(define list (readnums N))

(define (get-result list)
  (define (s list left num res)
    (define (f left right num)
      (define (lp left right num res)
        (if (< left right)
            res
            (lp (- left 1) right num (+ res (f left right (- num 1))))))
      (if (= num 1)
          (+ 1 (- left right))
          (lp left right num 0)))
          
    (cond 
      ((null? list) res)
      ((= (car list) -1) (s (cdr list) left (+ num 1) res))
      ((not (= num 0)) (s (cdr list) (car list) 0 (modulo (* res (f left (car list) num)) 1000000007)))
      (else (s (cdr list) (car list) 0 res))))
  (s list (car list) 0 1))


(display (get-result list))
(display "\n")

Submission Info

Judge Result