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// // Copyright 2012 The Go Authors. All rights reserved.
// // Use of this source code is governed by a BSD-style
// // license that can be found in the LICENSE file.
// package rand_test
// import (
// "fmt"
// "math/rand"
// "os"
// "strings"
// "text/tabwriter"
// )
// // These tests serve as an example but also make sure we don't change
// // the output of the random number generator when given a fixed seed.
// func Example() {
// answers := []string{
// "It is certain",
// "It is decidedly so",
// "Without a doubt",
// "Yes definitely",
// "You may rely on it",
// "As I see it yes",
// "Most likely",
// "Outlook good",
// "Yes",
// "Signs point to yes",
// "Reply hazy try again",
// "Ask again later",
// "Better not tell you now",
// "Cannot predict now",
// "Concentrate and ask again",
// "Don't count on it",
// "My reply is no",
// "My sources say no",
// "Outlook not so good",
// "Very doubtful",
// }
// fmt.Println("Magic 8-Ball says:", answers[rand.Intn(len(answers))])
// }
// // This example shows the use of each of the methods on a *Rand.
// // The use of the global functions is the same, without the receiver.
// func Example_rand() {
// // Create and seed the generator.
// // Typically a non-fixed seed should be used, such as time.Now().unix_nano().
// // Using a fixed seed will produce the same output on every run.
// r := rand.New(rand.NewSource(99))
// // The tabwriter here helps us generate aligned output.
// w := tabwriter.NewWriter(os.Stdout, 1, 1, 1, ' ', 0)
// defer w.Flush()
// show := func(name string, v1, v2, v3 any) {
// fmt.Fprintf(w, "%s\t%v\t%v\t%v\n", name, v1, v2, v3)
// }
// // Float32 and Float64 values are in [0, 1).
// show("Float32", r.Float32(), r.Float32(), r.Float32())
// show("Float64", r.Float64(), r.Float64(), r.Float64())
// // ExpFloat64 values have an average of 1 but decay exponentially.
// show("ExpFloat64", r.ExpFloat64(), r.ExpFloat64(), r.ExpFloat64())
// // norm_float64 values have an average of 0 and a standard deviation of 1.
// show("norm_float64", r.norm_float64(), r.norm_float64(), r.norm_float64())
// // Int31, Int63, and Uint32 generate values of the given width.
// // The Int method (not shown) is like either Int31 or Int63
// // depending on the size of 'int'.
// show("Int31", r.Int31(), r.Int31(), r.Int31())
// show("Int63", r.Int63(), r.Int63(), r.Int63())
// show("Uint32", r.Uint32(), r.Uint32(), r.Uint32())
// // Intn, Int31n, and Int63n limit their output to be < n.
// // They do so more carefully than using r.Int()%n.
// show("Intn(10)", r.Intn(10), r.Intn(10), r.Intn(10))
// show("Int31n(10)", r.Int31n(10), r.Int31n(10), r.Int31n(10))
// show("Int63n(10)", r.Int63n(10), r.Int63n(10), r.Int63n(10))
// // Perm generates a random permutation of the numbers [0, n).
// show("Perm", r.Perm(5), r.Perm(5), r.Perm(5))
// // Output:
// // Float32 0.2635776 0.6358173 0.6718283
// // Float64 0.628605430454327 0.4504798828572669 0.9562755949377957
// // ExpFloat64 0.3362240648200941 1.4256072328483647 0.24354758816173044
// // norm_float64 0.17233959114940064 1.577014951434847 0.04259129641113857
// // Int31 1501292890 1486668269 182840835
// // Int63 3546343826724305832 5724354148158589552 5239846799706671610
// // Uint32 2760229429 296659907 1922395059
// // Intn(10) 1 2 5
// // Int31n(10) 4 7 8
// // Int63n(10) 7 6 3
// // Perm [1 4 2 3 0] [4 2 1 3 0] [1 2 4 0 3]
// }
// func ExamplePerm() {
// for _, value := range rand.Perm(3) {
// fmt.Println(value)
// }
// // Unordered output: 1
// // 2
// // 0
// }
// func ExampleShuffle() {
// words := strings.Fields("ink runs from the corners of my mouth")
// rand.Shuffle(len(words), func(i, j int) {
// words[i], words[j] = words[j], words[i]
// })
// fmt.Println(words)
// }
// func ExampleShuffle_slicesInUnison() {
// numbers := []byte("12345")
// letters := []byte("ABCDE")
// // Shuffle numbers, swapping corresponding entries in letters at the same time.
// rand.Shuffle(len(numbers), func(i, j int) {
// numbers[i], numbers[j] = numbers[j], numbers[i]
// letters[i], letters[j] = letters[j], letters[i]
// })
// for i := range numbers {
// fmt.Printf("%c: %c\n", letters[i], numbers[i])
// }
// }
// func ExampleIntn() {
// fmt.Println(rand.Intn(100))
// fmt.Println(rand.Intn(100))
// fmt.Println(rand.Intn(100))
// }