Problem Statement

Show a nested loop which searches a two-dimensional array filled with random numbers uniformly distributed over

[ 1 , … , 20 ]

{\displaystyle [1,\ldots ,20]}

. The loops iterate rows and columns of the array printing the elements until the value

20

{\displaystyle 20}

is met. Specifically, this task also shows how to break out of nested loops.

Let's start with the solution:

#lang racket
(define (scan xss)
  (for* ([xs xss]
         [x  xs]
         #:final (= x 20))
    (displayln x)))

(define matrix
  (for/list ([x 10])
    (for/list ([y 10])
      (+ (random 20) 1))))

(scan matrix)