66 lines
1.3 KiB
Go
66 lines
1.3 KiB
Go
package xrand
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import (
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randx "crypto/rand"
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"math"
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"math/big"
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"math/rand"
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)
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var rd *rand.Rand
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func init() {
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rd = rand.New(rand.NewSource(randInt64()))
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}
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// 用系统熵构建更自然的随机数，比"math/rand"构建的线性同余自然随机数要慢
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func randInt64() int64 {
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n, _ := randx.Int(randx.Reader, big.NewInt(math.MaxInt64))
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return n.Int64()
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}
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// 随机值
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func Rand[T int | int32 | int64 | uint32 | uint64]() T {
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return T(randInt64())
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}
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// 从[0,n)范围里随机值
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func RandN[T int | int32 | int64 | uint | uint32 | uint64](n T) T {
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if int64(n) < 1 {
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return 0
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}
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return T(randInt64() % int64(n)) // [0,n) 的随机整数
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}
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// 从[min,max)范围里随机值
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func RandRange[T int | int32 | int64 | uint32 | uint64](min, max T) T {
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if int64(max) < 1 || int64(min) < 1 || max < min {
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return 0
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}
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return RandN[T](max-min) + min
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}
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func Perm(n int) []int {
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return rd.Perm(n)
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}
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func Read(p []byte) (n int, err error) {
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return rd.Read(p)
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}
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func Shuffle[T any](slice []T) {
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rand.Shuffle(len(slice), func(i, j int) {
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slice[i], slice[j] = slice[j], slice[i]
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})
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}
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const letterBytes = "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789"
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func RandomString(n int) string {
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b := make([]byte, n)
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for i := range b {
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b[i] = letterBytes[rd.Intn(len(letterBytes))]
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}
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return string(b)
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}
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