From 77e130ec340ad1af53bdeb099ddf768f8bca4a1b Mon Sep 17 00:00:00 2001
From: James Raspass <jraspass@gmail.com>
Date: Mon, 5 Jul 2021 22:35:23 +0100
Subject: [PATCH] Make "Spelling Numbers" exhaustive

Should hopefully fix this hole being cheeseable.

Updates #448
---
 hole/spelling-numbers.go      | 85 ++++++++++++-----------------------
 hole/spelling-numbers_test.go |  9 ++++
 2 files changed, 37 insertions(+), 57 deletions(-)
 create mode 100644 hole/spelling-numbers_test.go

diff --git a/hole/spelling-numbers.go b/hole/spelling-numbers.go
index e8d35e888..f6a83e8c3 100644
--- a/hole/spelling-numbers.go
+++ b/hole/spelling-numbers.go
@@ -3,6 +3,7 @@ package hole
 import (
 	"math/rand"
 	"strconv"
+	"strings"
 )
 
 var teens = [][]byte{
@@ -41,77 +42,47 @@ var tens = [][]byte{
 	[]byte("ninety"),
 }
 
-func wordify(i uint16) []byte {
+func wordify(out *strings.Builder, i int) {
 	if i == 1000 {
-		return []byte("one thousand")
+		out.WriteString("one thousand")
 	} else if i < 20 {
-		return teens[i]
+		out.Write(teens[i])
 	} else if i < 100 {
+		out.Write(tens[i/10])
+
 		if j := i % 10; j > 0 {
-			return append(append(append([]byte(nil), tens[i/10]...), '-'), teens[j]...)
+			out.WriteRune('-')
+			out.Write(teens[j])
 		}
+	} else {
+		out.Write(teens[i/100])
+		out.WriteString(" hundred")
 
-		return tens[i/10]
-	}
-
-	hundred := append(append([]byte(nil), teens[i/100]...), []byte(" hundred")...)
-
-	if j := i % 100; j > 0 {
-		hundred = append(append(hundred, []byte(" and ")...), wordify(j)...)
+		if j := i % 100; j > 0 {
+			out.WriteString(" and ")
+			wordify(out, j)
+		}
 	}
-
-	return hundred
 }
 
-func spellingNumbers() (args []string, out string) {
-	// Always test the low and high end.
-	numbers := []uint16{
-		0, 1, 2, 3, 4, 5, 6, 7, 8, 9,
-		10, 11, 12, 13, 14, 15, 16, 17, 18, 19,
-		20, 21, 29, 31,
-		901, 910, 911, 919, 920, 921,
-		990, 991, 992, 993, 994, 995, 996, 997, 998, 999, 1000,
-	}
-
-	tens := []uint16{20, 30, 40, 50, 60, 70, 80, 90}
+func spellingNumbers() ([]string, string) {
+	const max = 1000
 
-	rand.Shuffle(len(tens), func(i, j int) {
-		tens[i], tens[j] = tens[j], tens[i]
-	})
+	args := make([]string, max+1)
+	var out strings.Builder
 
-	// Add on random numbers to each ten except the first, to ensure at least
-	// one non hyphen answer.
-	for i := 1; i < len(tens); i++ {
-		tens[i] += 1 + uint16(rand.Intn(8))
-	}
-
-	numbers = append(numbers, tens...)
-
-	hundreds := []uint16{100, 200, 300, 400, 500, 600, 700, 800, 900}
-
-	rand.Shuffle(len(hundreds), func(i, j int) {
-		hundreds[i], hundreds[j] = hundreds[j], hundreds[i]
-	})
+	// The strings "zero" to "one thousand", newline delimited, are this len.
+	out.Grow(25531)
 
-	// Add on random numbers to each hundred except the first, to ensure at
-	// least one non and answer.
-	for i := 1; i < len(hundreds); i++ {
-		hundreds[i] += 1 + uint16(rand.Intn(98))
-	}
-
-	numbers = append(numbers, hundreds...)
+	for i, n := range rand.Perm(max + 1) {
+		args[i] = strconv.Itoa(n)
 
-	rand.Shuffle(len(numbers), func(i, j int) {
-		numbers[i], numbers[j] = numbers[j], numbers[i]
-	})
+		wordify(&out, n)
 
-	for _, n := range numbers {
-		args = append(args, strconv.Itoa(int(n)))
-		out += string(wordify(n)) + "\n"
+		if i < max {
+			out.WriteRune('\n')
+		}
 	}
 
-	// Drop the trailing newline.
-	out = out[:len(out)-1]
-
-	return
+	return args, out.String()
 }
diff --git a/hole/spelling-numbers_test.go b/hole/spelling-numbers_test.go
new file mode 100644
index 000000000..856547db3
--- /dev/null
+++ b/hole/spelling-numbers_test.go
@@ -0,0 +1,9 @@
+package hole
+
+import "testing"
+
+func BenchmarkSpellingNumbers(b *testing.B) {
+	for n := 0; n < b.N; n++ {
+		spellingNumbers()
+	}
+}