常见排序算法

目录

• 一、排序算法
  • 1.1 快速排序
  • 1.2 归并排序
  • 1.3 堆排序

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本文介绍了Go语言版经典的排序算法–快速排序、归并排序和堆排序。

一、排序算法

1.1 快速排序

func quickSort(data []int) {
	if len(data) <= 1 {
		return
	}
	base := data[0]
	l, r := 0, len(data)-1
	for i := 1; i <= r; {
		if data[i] > base {
			data[i], data[r] = data[r], data[i]
			r--
		} else {
			data[i], data[l] = data[l], data[i]
			l++
			i++
		}
	}
	quickSort(data[:l])
	quickSort(data[l+1:])
}

func main() {
	s := make([]int, 0, 16)
	for i := 0; i < 16; i++ {
		s = append(s, rand.Intn(100))
	}
	fmt.Println(s)
	quickSort(s)
	fmt.Println(s)
}

1.2 归并排序

func mergeSort(data []int) []int {
	length := len(data)
	if length <= 1 {
		return data
	}
	num := length / 2
	left := mergeSort(data[:num])
	right := mergeSort(data[num:])
	return merge(left, right)
}

func merge(left, right []int) (result []int) {
	l, r := 0, 0
	for l < len(left) && r < len(right) {
		if left[l] < right[r] {
			result = append(result, left[l])
			l++
		} else {
			result = append(result, right[r])
			r++
		}
	}
	result = append(result, left[l:]...)
	result = append(result, right[r:]...)
	return
}

func main() {
	s := make([]int, 0, 16)
	for i := 0; i < 16; i++ {
		s = append(s, rand.Intn(100))
	}
	fmt.Println(s)
	s = mergeSort(s)
	fmt.Println(s)
}

1.3 堆排序

func heapSort(array []int) {
	m := len(array)
	s := m / 2
	for i := s; i > -1; i-- {
		heap(array, i, m-1)
	}
	for i := m - 1; i > 0; i-- {
		array[i], array[0] = array[0], array[i]
		heap(array, 0, i-1)
	}
}
func heap(array []int, i, end int) {
	l := 2*i + 1
	if l > end {
		return
	}
	n := l
	r := 2*i + 2
	if r <= end && array[r] > array[l] {
		n = r
	}
	if array[i] > array[n] {
		return
	}
	array[n], array[i] = array[i], array[n]
	heap(array, n, end)
}
func main() {
	s := make([]int, 0, 16)
	for i := 0; i < 16; i++ {
		s = append(s, rand.Intn(100))
	}
	fmt.Println(s)
	heapSort(s)
	fmt.Println(s)
}