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https://github.com/gopl-zh/gopl-zh.github.com.git
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149 lines
3.2 KiB
Go
149 lines
3.2 KiB
Go
// Copyright © 2016 Alan A. A. Donovan & Brian W. Kernighan.
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// License: https://creativecommons.org/licenses/by-nc-sa/4.0/
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package word
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import (
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"fmt"
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"math/rand"
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"time"
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)
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//!+bench
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import "testing"
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//!-bench
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//!+test
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func TestIsPalindrome(t *testing.T) {
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var tests = []struct {
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input string
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want bool
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}{
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{"", true},
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{"a", true},
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{"aa", true},
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{"ab", false},
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{"kayak", true},
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{"detartrated", true},
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{"A man, a plan, a canal: Panama", true},
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{"Evil I did dwell; lewd did I live.", true},
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{"Able was I ere I saw Elba", true},
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{"été", true},
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{"Et se resservir, ivresse reste.", true},
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{"palindrome", false}, // non-palindrome
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{"desserts", false}, // semi-palindrome
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}
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for _, test := range tests {
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if got := IsPalindrome(test.input); got != test.want {
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t.Errorf("IsPalindrome(%q) = %v", test.input, got)
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}
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}
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}
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//!-test
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//!+bench
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func BenchmarkIsPalindrome(b *testing.B) {
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for i := 0; i < b.N; i++ {
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IsPalindrome("A man, a plan, a canal: Panama")
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}
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}
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//!-bench
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//!+example
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func ExampleIsPalindrome() {
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fmt.Println(IsPalindrome("A man, a plan, a canal: Panama"))
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fmt.Println(IsPalindrome("palindrome"))
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// Output:
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// true
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// false
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}
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//!-example
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/*
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//!+random
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import "math/rand"
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//!-random
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*/
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//!+random
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// randomPalindrome returns a palindrome whose length and contents
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// are derived from the pseudo-random number generator rng.
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func randomPalindrome(rng *rand.Rand) string {
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n := rng.Intn(25) // random length up to 24
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runes := make([]rune, n)
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for i := 0; i < (n+1)/2; i++ {
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r := rune(rng.Intn(0x1000)) // random rune up to '\u0999'
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runes[i] = r
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runes[n-1-i] = r
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}
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return string(runes)
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}
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func TestRandomPalindromes(t *testing.T) {
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// Initialize a pseudo-random number generator.
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seed := time.Now().UTC().UnixNano()
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t.Logf("Random seed: %d", seed)
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rng := rand.New(rand.NewSource(seed))
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for i := 0; i < 1000; i++ {
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p := randomPalindrome(rng)
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if !IsPalindrome(p) {
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t.Errorf("IsPalindrome(%q) = false", p)
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}
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}
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}
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//!-random
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/*
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// Answer for Exercicse 11.1: Modify randomPalindrome to exercise
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// IsPalindrome's handling of punctuation and spaces.
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// WARNING: the conversion r -> upper -> lower doesn't preserve
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// the value of r in some cases, e.g., µ Μ, ſ S, ı I
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// randomPalindrome returns a palindrome whose length and contents
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// are derived from the pseudo-random number generator rng.
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func randomNoisyPalindrome(rng *rand.Rand) string {
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n := rng.Intn(25) // random length up to 24
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runes := make([]rune, n)
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for i := 0; i < (n+1)/2; i++ {
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r := rune(rng.Intn(0x200)) // random rune up to \u99
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runes[i] = r
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r1 := r
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if unicode.IsLetter(r) && unicode.IsLower(r) {
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r = unicode.ToUpper(r)
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if unicode.ToLower(r) != r1 {
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fmt.Printf("cap? %c %c\n", r1, r)
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}
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}
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runes[n-1-i] = r
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}
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return "?" + string(runes) + "!"
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}
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func TestRandomNoisyPalindromes(t *testing.T) {
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// Initialize a pseudo-random number generator.
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seed := time.Now().UTC().UnixNano()
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t.Logf("Random seed: %d", seed)
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rng := rand.New(rand.NewSource(seed))
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n := 0
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for i := 0; i < 1000; i++ {
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p := randomNoisyPalindrome(rng)
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if !IsPalindrome(p) {
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t.Errorf("IsNoisyPalindrome(%q) = false", p)
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n++
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}
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}
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fmt.Fprintf(os.Stderr, "fail = %d\n", n)
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}
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*/
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