Problem Set 7

Language: Intermediate Student with lambda
Due: 11:59 PM Friday, March 22

1 Accumulators

Write the function

  ; to10: list-of-number -> number

from HTDP/1e exercise 31.3.7 using a helper function that takes an accumulator. The empty list of digits corresponds to the number 0.

You do not need to write the to10-general function mentioned in the exercise.

2 Graphs

Write the following two functions.

; a graph is

; (make-graph (listof symbol) (symbol -> (listof symbol)))

(define-struct graph (nodes neighbor))

; has-self-loop? : graph -> boolean

; Determines whether any node in the given graph is its own neighbor

; has-cycle? : graph -> boolean

; Determines whether the given graph has a cycle.

A cycle is a path from a node to itself, and a self-loop is a special case of a cycle that consists of only a single edge.