Merge pull request #451 from coriolinus/book-store-no-floats

book-store: use integer number of cents, not floating-point numbers

Author: coriolinus

exercises/book-store/Cargo-example.toml

@@ -1,7 +1,6 @@
 [package]
 name = "book_store"
-version = "1.0.1"
+version = "1.3.0"
 authors = ["Peter Goodspeed-Niklaus <[email protected]>"]
 
 [dependencies]
-noisy_float = "0.1.2"

exercises/book-store/Cargo.toml

@@ -1,6 +1,6 @@
 [package]
 name = "book_store"
-version = "1.1.0"
+version = "1.3.0"
 authors = ["Peter Goodspeed-Niklaus <[email protected]>"]
 
 [dependencies]

exercises/book-store/example.rs

@@ -5,13 +5,10 @@ use std::hash::{Hash, Hasher};
 use std::mem;
 use std::cell::RefCell;
 
-extern crate noisy_float;
-use noisy_float::prelude::*;
-
 type Book = usize;
 type GroupedBasket = Vec<Group>;
-type Price = f64;
-const BOOK_PRICE: Price = 8.0;
+type Price = usize;
+const BOOK_PRICE: Price = 800;
 
 #[derive(Debug, Clone, PartialEq, Eq)]
 struct Group(RefCell<BTreeSet<Book>>);
@@ -30,12 +27,12 @@ impl Group {
     fn price(&self) -> Price {
         (self.0.borrow().len() as Price) * BOOK_PRICE *
             match self.0.borrow().len() {
-                2 => 0.95,
-                3 => 0.90,
-                4 => 0.80,
-                5 => 0.75,
-                _ => 1.0,
-            }
+                2 => 95,
+                3 => 90,
+                4 => 80,
+                5 => 75,
+                _ => 100,
+            } / 100
     }
 }
 
@@ -96,10 +93,9 @@ fn hash_of(basket: &GroupedBasket) -> u64 {
 
 pub fn lowest_price(books: &[Book]) -> Price {
     DecomposeGroups::new(books)
-        .map(|gb| r64(basket_price(&gb)))
+        .map(|gb| basket_price(&gb))
         .min()
-        .map(|r| r.raw())
-        .unwrap_or(0.0)
+        .unwrap_or(0)
 }
 
 struct DecomposeGroups {

exercises/book-store/src/lib.rs

@@ -1,3 +1,3 @@
-pub fn lowest_price(_: &[usize]) -> f64 {
+pub fn lowest_price(_: &[usize]) -> usize {
     unimplemented!()
 }

exercises/book-store/tests/book-store.rs

@@ -14,7 +14,7 @@ use book_store::*;
 /// in terms of this function.
 ///
 /// Expected input format: ('basket', 'targetgrouping')
-fn process_total_case(input: (Vec<usize>, Vec<Vec<usize>>), expected: f64) {
+fn process_total_case(input: (Vec<usize>, Vec<Vec<usize>>), expected: usize) {
     assert_eq!(
         lowest_price(&input.0),
         expected
@@ -30,108 +30,108 @@ fn process_total_case(input: (Vec<usize>, Vec<Vec<usize>>), expected: f64) {
 #[test]
 /// Only a single book
 fn test_only_a_single_book() {
-    process_total_case((vec![1], vec![vec![1]]), 8.0);
+    process_total_case((vec![1], vec![vec![1]]), 800);
 }
 
 
 #[test]
 #[ignore]
 /// Two of the same book
 fn test_two_of_the_same_book() {
-    process_total_case((vec![2, 2], vec![vec![2], vec![2]]), 16.0);
+    process_total_case((vec![2, 2], vec![vec![2], vec![2]]), 1_600);
 }
 
 
 #[test]
 #[ignore]
 /// Empty basket
 fn test_empty_basket() {
-    process_total_case((vec![], vec![]), 0.0);
+    process_total_case((vec![], vec![]), 0);
 }
 
 
 #[test]
 #[ignore]
 /// Two different books
 fn test_two_different_books() {
-    process_total_case((vec![1, 2], vec![vec![1, 2]]), 15.2);
+    process_total_case((vec![1, 2], vec![vec![1, 2]]), 1_520);
 }
 
 
 #[test]
 #[ignore]
 /// Three different books
 fn test_three_different_books() {
-    process_total_case((vec![1, 2, 3], vec![vec![1, 2, 3]]), 21.6);
+    process_total_case((vec![1, 2, 3], vec![vec![1, 2, 3]]), 2_160);
 }
 
 
 #[test]
 #[ignore]
 /// Four different books
 fn test_four_different_books() {
-    process_total_case((vec![1, 2, 3, 4], vec![vec![1, 2, 3, 4]]), 25.6);
+    process_total_case((vec![1, 2, 3, 4], vec![vec![1, 2, 3, 4]]), 2_560);
 }
 
 
 #[test]
 #[ignore]
 /// Five different books
 fn test_five_different_books() {
-    process_total_case((vec![1, 2, 3, 4, 5], vec![vec![1, 2, 3, 4, 5]]), 30.0);
+    process_total_case((vec![1, 2, 3, 4, 5], vec![vec![1, 2, 3, 4, 5]]), 3_000);
 }
 
 
 #[test]
 #[ignore]
 /// Two groups of four is cheaper than group of five plus group of three
 fn test_two_groups_of_four_is_cheaper_than_group_of_five_plus_group_of_three() {
-    process_total_case((vec![1, 1, 2, 2, 3, 3, 4, 5], vec![vec![1, 2, 3, 4], vec![1, 2, 3, 5]]), 51.2);
+    process_total_case((vec![1, 1, 2, 2, 3, 3, 4, 5], vec![vec![1, 2, 3, 4], vec![1, 2, 3, 5]]), 5_120);
 }
 
 
 #[test]
 #[ignore]
 /// Group of four plus group of two is cheaper than two groups of three
 fn test_group_of_four_plus_group_of_two_is_cheaper_than_two_groups_of_three() {
-    process_total_case((vec![1, 1, 2, 2, 3, 4], vec![vec![1, 2, 3, 4], vec![1, 2]]), 40.8);
+    process_total_case((vec![1, 1, 2, 2, 3, 4], vec![vec![1, 2, 3, 4], vec![1, 2]]), 4_080);
 }
 
 
 #[test]
 #[ignore]
 /// Two each of first 4 books and 1 copy each of rest
 fn test_two_each_of_first_4_books_and_1_copy_each_of_rest() {
-    process_total_case((vec![1, 1, 2, 2, 3, 3, 4, 4, 5], vec![vec![1, 2, 3, 4, 5], vec![1, 2, 3, 4]]), 55.6);
+    process_total_case((vec![1, 1, 2, 2, 3, 3, 4, 4, 5], vec![vec![1, 2, 3, 4, 5], vec![1, 2, 3, 4]]), 5_560);
 }
 
 
 #[test]
 #[ignore]
 /// Two copies of each book
 fn test_two_copies_of_each_book() {
-    process_total_case((vec![1, 1, 2, 2, 3, 3, 4, 4, 5, 5], vec![vec![1, 2, 3, 4, 5], vec![1, 2, 3, 4, 5]]), 60.0);
+    process_total_case((vec![1, 1, 2, 2, 3, 3, 4, 4, 5, 5], vec![vec![1, 2, 3, 4, 5], vec![1, 2, 3, 4, 5]]), 6_000);
 }
 
 
 #[test]
 #[ignore]
 /// Three copies of first book and 2 each of remaining
 fn test_three_copies_of_first_book_and_2_each_of_remaining() {
-    process_total_case((vec![1, 1, 2, 2, 3, 3, 4, 4, 5, 5, 1], vec![vec![1, 2, 3, 4, 5], vec![1, 2, 3, 4, 5], vec![1]]), 68.0);
+    process_total_case((vec![1, 1, 2, 2, 3, 3, 4, 4, 5, 5, 1], vec![vec![1, 2, 3, 4, 5], vec![1, 2, 3, 4, 5], vec![1]]), 6_800);
 }
 
 
 #[test]
 #[ignore]
 /// Three each of first 2 books and 2 each of remaining books
 fn test_three_each_of_first_2_books_and_2_each_of_remaining_books() {
-    process_total_case((vec![1, 1, 2, 2, 3, 3, 4, 4, 5, 5, 1, 2], vec![vec![1, 2, 3, 4, 5], vec![1, 2, 3, 4, 5], vec![1, 2]]), 75.2);
+    process_total_case((vec![1, 1, 2, 2, 3, 3, 4, 4, 5, 5, 1, 2], vec![vec![1, 2, 3, 4, 5], vec![1, 2, 3, 4, 5], vec![1, 2]]), 7_520);
 }
 
 #[test]
 #[ignore]
 /// Four groups of four are cheaper than two groups each of five and three
 fn test_four_groups_of_four_are_cheaper_than_two_groups_each_of_five_and_three() {
-    process_total_case((vec![1,1,2,2,3,3,4,5,1,1,2,2,3,3,4,5], vec![vec![1,2,3,4],vec![1,2,3,5],vec![1,2,3,4],vec![1,2,3,5]]), 102.4);
+    process_total_case((vec![1,1,2,2,3,3,4,5,1,1,2,2,3,3,4,5], vec![vec![1,2,3,4],vec![1,2,3,5],vec![1,2,3,4],vec![1,2,3,5]]), 10_240);
 }