feat: math.

rand/rand.go

@@ -3,16 +3,50 @@ package rand
 import (
 	"math/rand"
 	"time"
+
+	"github.com/tx7do/go-utils/math"
 )
 
-var RANDOM = rand.New(rand.NewSource(time.Now().UnixNano()))
+var rnd = rand.New(rand.NewSource(time.Now().UnixNano()))
+
+func init() {
+	rnd = rand.New(rand.NewSource(time.Now().UnixNano()))
+}
+
+func Float32() float32 {
+	return rnd.Float32()
+}
+
+func Float64() float64 {
+	return rnd.Float64()
+}
+
+func Intn(n int) int {
+	return rnd.Intn(n)
+}
+
+func Int31n(n int32) int32 {
+	return rnd.Int31n(n)
+}
+
+func Int63n(n int64) int64 {
+	return rnd.Int63n(n)
+}
 
 // RandomInt 根据区间产生随机数
 func RandomInt(min, max int) int {
 	if min >= max {
 		return max
 	}
-	return RANDOM.Intn(max-min) + min
+	return min + Intn(max-min+1)
+}
+
+// RandomInt32 根据区间产生随机数
+func RandomInt32(min, max int32) int32 {
+	if min >= max {
+		return max
+	}
+	return min + Int31n(max-min+1)
 }
 
 // RandomInt64 根据区间产生随机数
@@ -20,5 +54,96 @@ func RandomInt64(min, max int64) int64 {
 	if min >= max {
 		return max
 	}
-	return RANDOM.Int63n(max-min) + min
+	return min + Int63n(max-min+1)
+}
+
+// RandomString 随机字符串，包含大小写字母和数字
+func RandomString(l int) string {
+	bytes := make([]byte, l)
+	for i := 0; i < l; i++ {
+		x := Intn(3)
+		switch x {
+		case 0:
+			bytes[i] = byte(RandomInt(65, 90)) //大写字母
+		case 1:
+			bytes[i] = byte(RandomInt(97, 122))
+		case 2:
+			bytes[i] = byte(Intn(10))
+		}
+	}
+	return string(bytes)
+}
+
+// RandomChoice 随机选择数组中的元素
+func RandomChoice[T any](array []T, n int) []T {
+	if n <= 0 {
+		return nil
+	}
+	if n == 1 {
+		return []T{array[Intn(len(array))]}
+	}
+
+	tmp := make([]T, len(array))
+	copy(tmp, array)
+	if len(tmp) <= n {
+		return tmp
+	}
+
+	Shuffle(tmp)
+
+	return tmp[:n]
+}
+
+// Shuffle 随机打乱数组
+func Shuffle[T any](array []T) {
+	if array == nil {
+		return
+	}
+
+	for i := range array {
+		j := Intn(i + 1)
+		array[i], array[j] = array[j], array[i]
+	}
+}
+
+// WeightedChoice 根据权重随机，返回对应选项的索引，O(n)
+func WeightedChoice(weightArray []int) int {
+	if weightArray == nil {
+		return -1
+	}
+
+	total := math.SumInt(weightArray)
+	rv := Int63n(total)
+	for i, v := range weightArray {
+		if rv < int64(v) {
+			return i
+		}
+		rv -= int64(v)
+	}
+
+	return len(weightArray) - 1
+}
+
+// NonWeightedChoice 根据权重随机，返回对应选项的索引，O(n). 权重大于等于0
+func NonWeightedChoice(weightArray []int) int {
+	if weightArray == nil {
+		return -1
+	}
+
+	for i, weight := range weightArray {
+		if weight < 0 {
+			weightArray[i] = 0
+		}
+	}
+
+	total := math.SumInt(weightArray)
+	rv := Int63n(total)
+	for i, v := range weightArray {
+		if rv < int64(v) {
+			return i
+		}
+		rv -= int64(v)
+	}
+
+	return len(weightArray) - 1
 }