cpt_lab5

#!/usr/bin/env racket
#lang racket

; n=10 - размерность матрицы

(define nth list-ref)

(define (diag-maxs-vec matrix)
    (define (iter i vec)
      (if (= i 19)
        vec
        (iter (add1 i)
              (cons (apply max (diag matrix i)) vec))))
    (iter 0 '()))

(define (diag matrix n)
  (let ((beg (diag-beg n))
        (end (coord-move-diag (diag-end n))))
    (define (iter p d)
      (if (equal? p end)
        d
        (iter (coord-move-diag p) (cons (matrix-elem matrix p) d))))
    (iter beg '())))

(define (diag-beg n)
  (make-coord (max (- 9 n) 0)
              (max (- n 9) 0)))

(define (diag-end n)
  (make-coord (min (- 18 n) 9)
              (min n 9)))

(define (matrix-elem matrix coord)
  (nth (nth matrix
            (coord-i coord))
       (coord-j coord)))

(define (make-coord i j)
  (cons i j))

(define (coord-i c)
  (car c))

(define (coord-j c)
  (cdr c))

(define (coord-move-diag c)
  (make-coord (add1 (coord-i c)) (add1 (coord-j c))))


(define matrix (list (list 1 2 3 4 5 6 7 8 9 10)
                     (list 1 2 3 4 5 6 7 8 9 10)
                     (list 1 2 3 4 5 6 7 8 9 10)
                     (list 1 2 3 4 5 6 7 8 9 10)
                     (list 1 2 3 4 5 6 7 8 9 10)
                     (list 1 2 3 4 5 6 7 8 9 10)
                     (list 1 2 3 4 5 6 7 8 9 10)
                     (list 1 2 3 4 5 6 7 8 9 10)
                     (list 1 2 3 4 5 6 7 8 9 10)
                     (list 1 2 3 4 5 6 7 8 9 10)))

(diag-maxs-vec matrix)
(length (diag-maxs-vec matrix))