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fix parapllel merge sort

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This commit is contained in:
Gregory 2021-12-29 23:59:49 +02:00
parent 1f81f4cb45
commit 39992e2a9c
1 changed files with 6 additions and 6 deletions
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12
sorting/merge.go
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@ -29,7 +29,7 @@ func merge[T any](items []T, low, mid, hig int, less func(a, b T) bool, aux []T)
} }
func doSort[T any](items []T, low, hig int, less func(a, b T) bool, aux []T) { func doMergeSort[T any](items []T, low, hig int, less func(a, b T) bool, aux []T) {
if hig <= low { if hig <= low {
return return
} }
@ -44,8 +44,8 @@ func doSort[T any](items []T, low, hig int, less func(a, b T) bool, aux []T) {
mid := low + (hig-low)/2 mid := low + (hig-low)/2
doSort(items, low, mid, less, aux) doMergeSort(items, low, mid, less, aux)
doSort(items, mid+1, hig, less, aux) doMergeSort(items, mid+1, hig, less, aux)
// Optimization 1: if two subarrays already sorted // Optimization 1: if two subarrays already sorted
// we can skip merging them // we can skip merging them
@ -73,8 +73,8 @@ func doParallelSort[T any](items []T, low, hig int, less func(a, b T) bool, aux
// usage by creating WaitGroup instances // usage by creating WaitGroup instances
wg := sync.WaitGroup{} wg := sync.WaitGroup{}
wg.Add(2) wg.Add(2)
go func() { doSort(items, low, mid, less, aux); wg.Done() }() go func() { doParallelSort(items, low, mid, less, aux); wg.Done() }()
go func() { doSort(items, mid+1, hig, less, aux); wg.Done() }() go func() { doParallelSort(items, mid+1, hig, less, aux); wg.Done() }()
wg.Wait() wg.Wait()
if less(items[mid], items[mid+1]) { if less(items[mid], items[mid+1]) {
@ -88,7 +88,7 @@ func Merge[T any](items []T, less func(a, b T) bool) {
len := len(items) len := len(items)
doSort(items, 0, len-1, less, make([]T, len)) doMergeSort(items, 0, len-1, less, make([]T, len))
} }
func ParallelMerge[T any](items []T, less func(a, b T) bool) { func ParallelMerge[T any](items []T, less func(a, b T) bool) {