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unit_sort.go
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unit_sort.go
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package botutil
import (
"github.com/chippydip/go-sc2ai/api"
)
func sortUnits(data *[]*api.Unit) {
//sort.Sort((*sorter)(data))
quickSort(*data, maxDepth(len(*data)))
// check sort
// prev := data[0].UnitType
// for _, uu := range data {
// if uu.UnitType < prev {
// panic("not sorted!")
// }
// prev = uu.UnitType
// }
}
// Generic sort.Interface wrapper
type sorter []*api.Unit
func (s *sorter) Len() int { return len(*s) }
func (s *sorter) Swap(i, j int) { (*s)[i], (*s)[j] = (*s)[j], (*s)[i] }
func (s *sorter) Less(i, j int) bool { return (*s)[i].UnitType < (*s)[j].UnitType }
// Type-specialized version of sort.Sort
func maxDepth(n int) int {
var depth int
for i := n; i > 0; i >>= 1 {
depth++
}
return depth * 2
}
func quickSort(data []*api.Unit, maxDepth int) {
for len(data) > 12 { // Use ShellSort for slices <= 12 elements
if maxDepth == 0 {
heapSort(data)
return
}
maxDepth--
mlo, mhi := doPivot(data)
// Avoiding recursion on the larger subproblem guarantees
// a stack depth of at most lg(b-a).
if mlo < len(data)-mhi {
quickSort(data[:mlo], maxDepth)
//a = mhi // i.e., quickSort(data, mhi, b)
data = data[mhi:]
} else {
quickSort(data[mhi:], maxDepth)
//b = mlo // i.e., quickSort(data, a, mlo)
data = data[:mlo]
}
}
if len(data) > 1 {
// Do ShellSort pass with gap 6
// It could be written in this simplified form cause b-a <= 12
for i := 6; i < len(data); i++ {
if data[i].UnitType < data[i-6].UnitType {
data[i], data[i-6] = data[i-6], data[i]
}
}
insertionSort(data)
}
}
func heapSort(data []*api.Unit) {
first := 0
lo := 0
hi := len(data)
// Build heap with greatest element at top.
for i := (hi - 1) / 2; i >= 0; i-- {
siftDown(data, i, hi, first)
}
// Pop elements, largest first, into end of data.
for i := hi - 1; i >= 0; i-- {
data[first], data[first+i] = data[first+i], data[first]
siftDown(data, lo, i, first)
}
}
func siftDown(data []*api.Unit, lo, hi, first int) {
root := lo
for {
child := 2*root + 1
if child >= hi {
break
}
if child+1 < hi && data[first+child].UnitType < data[first+child+1].UnitType {
child++
}
if data[first+root].UnitType >= data[first+child].UnitType {
return
}
data[first+root], data[first+child] = data[first+child], data[first+root]
root = child
}
}
func insertionSort(data []*api.Unit) {
for i := 0 + 1; i < len(data); i++ {
for j := i; j > 0 && data[j].UnitType < data[j-1].UnitType; j-- {
data[j], data[j-1] = data[j-1], data[j]
}
}
}
func doPivot(data []*api.Unit) (midlo, midhi int) {
m := len(data) / 2
if len(data) > 40 {
// Tukey's ``Ninther,'' median of three medians of three.
s := len(data) / 8
medianOfThree(data, 0, 0+s, 0+2*s)
medianOfThree(data, m, m-s, m+s)
medianOfThree(data, len(data)-1, len(data)-1-s, len(data)-1-2*s)
}
medianOfThree(data, 0, m, len(data)-1)
// Invariants are:
// data[lo] = pivot (set up by ChoosePivot)
// data[lo < i < a] < pivot
// data[a <= i < b] <= pivot
// data[b <= i < c] unexamined
// data[c <= i < hi-1] > pivot
// data[hi-1] >= pivot
pivot := 0
a, c := 0+1, len(data)-1
for ; a < c && data[a].UnitType < data[pivot].UnitType; a++ {
}
b := a
for {
for ; b < c && data[pivot].UnitType >= data[b].UnitType; b++ { // data[b] <= pivot
}
for ; b < c && data[pivot].UnitType < data[c-1].UnitType; c-- { // data[c-1] > pivot
}
if b >= c {
break
}
// data[b] > pivot; data[c-1] <= pivot
data[b], data[c-1] = data[c-1], data[b]
b++
c--
}
// If hi-c<3 then there are duplicates (by property of median of nine).
// Let be a bit more conservative, and set border to 5.
protect := len(data)-c < 5
if !protect && len(data)-c < len(data)/4 {
// Lets test some points for equality to pivot
dups := 0
if data[pivot].UnitType >= data[len(data)-1].UnitType { // data[hi-1] = pivot
data[c], data[len(data)-1] = data[len(data)-1], data[c]
c++
dups++
}
if data[b-1].UnitType >= data[pivot].UnitType { // data[b-1] = pivot
b--
dups++
}
// m-lo = (hi-lo)/2 > 6
// b-lo > (hi-lo)*3/4-1 > 8
// ==> m < b ==> data[m] <= pivot
if data[m].UnitType >= data[pivot].UnitType { // data[m] = pivot
data[m], data[b-1] = data[b-1], data[m]
b--
dups++
}
// if at least 2 points are equal to pivot, assume skewed distribution
protect = dups > 1
}
if protect {
// Protect against a lot of duplicates
// Add invariant:
// data[a <= i < b] unexamined
// data[b <= i < c] = pivot
for {
for ; a < b && data[b-1].UnitType >= data[pivot].UnitType; b-- { // data[b] == pivot
}
for ; a < b && data[a].UnitType < data[pivot].UnitType; a++ { // data[a] < pivot
}
if a >= b {
break
}
// data[a] == pivot; data[b-1] < pivot
data[a], data[b-1] = data[b-1], data[a]
a++
b--
}
}
// Swap pivot into middle
data[pivot], data[b-1] = data[b-1], data[pivot]
return b - 1, c
}
func medianOfThree(data []*api.Unit, m1, m0, m2 int) {
// sort 3 elements
if data[m1].UnitType < data[m0].UnitType {
data[m1], data[m0] = data[m0], data[m1]
}
// data[m0] <= data[m1]
if data[m2].UnitType < data[m1].UnitType {
data[m2], data[m1] = data[m1], data[m2]
// data[m0] <= data[m2] && data[m1] < data[m2]
if data[m1].UnitType < data[m0].UnitType {
data[m1], data[m0] = data[m0], data[m1]
}
}
// now data[m0] <= data[m1] <= data[m2]
}