diff --git a/config.json b/config.json index eba7db2..35cd111 100644 --- a/config.json +++ b/config.json @@ -230,6 +230,14 @@ "prerequisites": [], "difficulty": 2 }, + { + "slug": "nth-prime", + "name": "Nth Prime", + "uuid": "ae46d5df-62cc-46d8-a773-bc93a1ad716e", + "practices": [], + "prerequisites": [], + "difficulty": 2 + }, { "slug": "nucleotide-count", "name": "Nucleotide Count", diff --git a/exercises/practice/nth-prime/.docs/instructions.md b/exercises/practice/nth-prime/.docs/instructions.md new file mode 100644 index 0000000..065e323 --- /dev/null +++ b/exercises/practice/nth-prime/.docs/instructions.md @@ -0,0 +1,7 @@ +# Instructions + +Given a number n, determine what the nth prime is. + +By listing the first six prime numbers: 2, 3, 5, 7, 11, and 13, we can see that the 6th prime is 13. + +If your language provides methods in the standard library to deal with prime numbers, pretend they don't exist and implement them yourself. diff --git a/exercises/practice/nth-prime/.meta/config.json b/exercises/practice/nth-prime/.meta/config.json new file mode 100644 index 0000000..340ee4a --- /dev/null +++ b/exercises/practice/nth-prime/.meta/config.json @@ -0,0 +1,19 @@ +{ + "authors": [ + "BNAndras" + ], + "files": { + "solution": [ + "nth-prime.rkt" + ], + "test": [ + "nth-prime-test.rkt" + ], + "example": [ + ".meta/example.rkt" + ] + }, + "blurb": "Given a number n, determine what the nth prime is.", + "source": "A variation on Problem 7 at Project Euler", + "source_url": "https://projecteuler.net/problem=7" +} diff --git a/exercises/practice/nth-prime/.meta/example.rkt b/exercises/practice/nth-prime/.meta/example.rkt new file mode 100644 index 0000000..2b23f9e --- /dev/null +++ b/exercises/practice/nth-prime/.meta/example.rkt @@ -0,0 +1,29 @@ +#lang racket + +(provide nth-prime) + +(define/contract (nth-prime number) + (-> exact-positive-integer? exact-positive-integer?) + (let loop ([candidate 2] + [count 0]) + (cond + [(prime? candidate) + (cond + [(= (add1 count) number) candidate] + [else (loop (add1 candidate) + (add1 count))])] + [else (loop (add1 candidate) + count)]))) + +(define (prime? number) + (cond + [(zero? number) #f] + [(= number 1) #f] + [(= number 2) #t] + [(even? number) #f] + [else + (let loop ([factor 3]) + (cond + [(> (expt factor 2) number) #t] + [(zero? (remainder number factor)) #f] + [else (loop (+ factor 2))]))])) \ No newline at end of file diff --git a/exercises/practice/nth-prime/.meta/tests.toml b/exercises/practice/nth-prime/.meta/tests.toml new file mode 100644 index 0000000..daccec4 --- /dev/null +++ b/exercises/practice/nth-prime/.meta/tests.toml @@ -0,0 +1,25 @@ +# This is an auto-generated file. +# +# Regenerating this file via `configlet sync` will: +# - Recreate every `description` key/value pair +# - Recreate every `reimplements` key/value pair, where they exist in problem-specifications +# - Remove any `include = true` key/value pair (an omitted `include` key implies inclusion) +# - Preserve any other key/value pair +# +# As user-added comments (using the # character) will be removed when this file +# is regenerated, comments can be added via a `comment` key. + +[75c65189-8aef-471a-81de-0a90c728160c] +description = "first prime" + +[2c38804c-295f-4701-b728-56dea34fd1a0] +description = "second prime" + +[56692534-781e-4e8c-b1f9-3e82c1640259] +description = "sixth prime" + +[fce1e979-0edb-412d-93aa-2c744e8f50ff] +description = "big prime" + +[bd0a9eae-6df7-485b-a144-80e13c7d55b2] +description = "there is no zeroth prime" diff --git a/exercises/practice/nth-prime/nth-prime-test.rkt b/exercises/practice/nth-prime/nth-prime-test.rkt new file mode 100644 index 0000000..b53cb94 --- /dev/null +++ b/exercises/practice/nth-prime/nth-prime-test.rkt @@ -0,0 +1,26 @@ +#lang racket/base + +(require "nth-prime.rkt") + +(module+ test + (require rackunit rackunit/text-ui) + + (define suite + (test-suite + "nth prime tests" + (test-equal? "first prime" + (nth-prime 1) + 2) + (test-equal? "second prime" + (nth-prime 2) + 3) + (test-equal? "sixth prime" + (nth-prime 6) + 13) + (test-equal? "big prime" + (nth-prime 10001) + 104743) + (test-exn "there is no zeroth prime" + exn:fail? (lambda () (nth-prime 0))))) + + (run-tests suite)) diff --git a/exercises/practice/nth-prime/nth-prime.rkt b/exercises/practice/nth-prime/nth-prime.rkt new file mode 100644 index 0000000..47232e6 --- /dev/null +++ b/exercises/practice/nth-prime/nth-prime.rkt @@ -0,0 +1,6 @@ +#lang racket + +(provide nth-prime) + +(define (nth-prime number) + (error "Not implemented yet"))