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fisher_yates_knuth_shuffle.go
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fisher_yates_knuth_shuffle.go
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package shuffle
import (
"math/rand"
"time"
)
// 使用自己独立的随机数生成器,与其它的调用区分开
var standaloneRand = rand.New(rand.NewSource(time.Now().Unix()))
// FisherYatesKnuthShuffle Fisher–Yates-Knuth Shuffle或 算法对一维数组洗牌,O(n)
func FisherYatesKnuthShuffle[T any](slice []T) {
for index := len(slice) - 1; index > 0; index-- {
chooseIndex := standaloneRand.Intn(index + 1)
slice[chooseIndex], slice[index] = slice[index], slice[chooseIndex]
}
}
// FisherYatesShuffleMatrix Fisher–Yates-Knuth shuffle算法对矩阵洗牌
func FisherYatesShuffleMatrix[T any](matrix [][]T) error {
// 参数检查
if err := check(matrix); err != nil {
return err
}
row, col := len(matrix), len(matrix[0])
for index := row*col - 1; index > 0; index-- {
chooseIndex := standaloneRand.Intn(index + 1)
matrix[index/col][index%col], matrix[chooseIndex/col][chooseIndex%col] = matrix[chooseIndex/col][chooseIndex%col], matrix[index/col][index%col]
}
return nil
}
// 需要保证传入的二维数据是一个矩阵,否则后面可能会越界panic
func check[T any](matrix [][]T) error {
for i := 1; i < len(matrix); i++ {
if len(matrix[i]) != len(matrix[i-1]) {
return ErrMatrixUnavailable
}
}
return nil
}