golang merge sort
package main
import (
"fmt"
"math/rand"
"time"
)
func main() {
slice := generateSlice(20)
fmt.Println("\n--- Unsorted --- \n\n", slice)
fmt.Println("\n--- Sorted ---\n\n", mergeSort(slice), "\n")
}
// Generates a slice of size, size filled with random numbers
func generateSlice(size int) []int {
slice := make([]int, size, size)
rand.Seed(time.Now().UnixNano())
for i := 0; i < size; i++ {
slice[i] = rand.Intn(999) - rand.Intn(999)
}
return slice
}
func mergeSort(items []int) []int {
var num = len(items)
if num == 1 {
return items
}
middle := int(num / 2)
var (
left = make([]int, middle)
right = make([]int, num-middle)
)
for i := 0; i < num; i++ {
if i < middle {
left[i] = items[i]
} else {
right[i-middle] = items[i]
}
}
return merge(mergeSort(left), mergeSort(right))
}
func merge(left, right []int) (result []int) {
result = make([]int, len(left) + len(right))
i := 0
for len(left) > 0 && len(right) > 0 {
if left[0] < right[0] {
result[i] = left[0]
left = left[1:]
} else {
result[i] = right[0]
right = right[1:]
}
i++
}
for j := 0; j < len(left); j++ {
result[i] = left[j]
i++
}
for j := 0; j < len(right); j++ {
result[i] = right[j]
i++
}
return
}