Go 語言實現堆排序與快速排序

• 堆排序

package main

import "fmt"

func buildHeap(arr []int) {
	length := len(arr)

	for i := length/2 - 1; i >= 0; i-- {
		toHeap(i, length-1, arr)
	}
}

func toHeap(i int, n int, arr []int) {
	max := i
	left := 2*i + 1
	right := 2*i + 2

	if left <= n && arr[max] < arr[left] {
		max = left
	}
	if right <= n && arr[max] < arr[right] {
		max = right
	}
	if max != i {
		arr[i], arr[max] = arr[max], arr[i]
		toHeap(max, n, arr)
	}
}

func heapSort(arr []int) {
	count := len(arr)
	buildHeap(arr)
	for count > 1 {
		arr[0], arr[count-1] = arr[count-1], arr[0]
		count--
		toBuild(arr, count-1, 0)
	}
}

func main() {
	arr := []int{1, 3, 2, 4, 5, 8, 6, 7}
	heapSort(arr)
	fmt.Println(arr)
}

---

• 快速排序

package main

import (
	"fmt"
)

func quickSort(arr []int) ([]int) {

	var left []int
	var right []int
	length := len(arr)
	if length <= 1 {
		return arr
	}
	base := arr[0]
	for i := 1; i < length; i++ {
		if base > arr[i] {
			left = append(left, arr[i])
		} else {
			right = append(right, arr[i])
		}
	}
	left = quickSort(left)
	right = quickSort(right)
	left = append(left, base)
	return append(left, right...)
}

func main() {

	arr := []int{9, 7, 8, 6, 4, 5, 1, 3, 2, 10, 356, 2123, 12, 2345345}
	fmt.Println(quickSort(arr))

}

• append(left, right...) 這裏 right... 是所以的 Go 的語法糖，slice 加 ... 代表數組解包的含義，類似與 PHP 的 list() 方法