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feat: add a third solution for shuffle experiment

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Add the third solution to the shuffle experiment which happens to be the
most performant solution according to the basic benchmark test.
This commit is contained in:
Dan Anglin 2024-01-24 23:33:37 +00:00
parent 3c9afeb1b9
commit 1b9c390ce6
Signed by: dananglin
GPG key ID: 0C1D44CFBEE68638
2 changed files with 86 additions and 18 deletions
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55
experiments/go/shuffle-elements/shuffle.go
View file

@ -10,7 +10,7 @@ const (
// shuffleFuncOne creates a new list where an element in one position is repositioned
// to the index of another element. All affected elements then shuffleFuncOne one place to the left
// or right depending on the direction of the move.
func shuffleFuncOne(list []any, oldPos, newPos int) []any {
func shuffleFuncOne(input []any, oldPos, newPos int) []any {
var direction shuffleDirection
if newPos < oldPos {
@ -19,54 +19,73 @@ func shuffleFuncOne(list []any, oldPos, newPos int) []any {
direction = left
}
newList := make([]any, len(list))
output := make([]any, len(input))
for i := range list {
for i := range input {
switch {
case (direction == right) && (i < newPos || i > oldPos):
newList[i] = list[i]
output[i] = input[i]
case (direction == right) && (i == oldPos):
newList[newPos] = list[i]
output[newPos] = input[i]
case (direction == right):
newList[i+1] = list[i]
output[i+1] = input[i]
case (direction == left) && (i < oldPos || i > newPos):
newList[i] = list[i]
output[i] = input[i]
case (direction == left) && (i == oldPos):
newList[newPos] = list[i]
output[newPos] = input[i]
case (direction == left):
newList[i-1] = list[i]
output[i-1] = input[i]
}
}
return newList
return output
}
// shuffleFuncTwo produces the same output as shuffleFuncOne using a slightly different method.
// The original slice is copied into a new slice and the element is immediately placed in the new
// position. The for loop then only focuses on the elements in range between the two positions and
// are shuffled left or right as required.
func shuffleFuncTwo(list []any, oldPos, newPos int) []any {
newList := make([]any, len(list))
func shuffleFuncTwo(input []any, oldPos, newPos int) []any {
output := make([]any, len(input))
copy(newList, list)
copy(output, input)
newList[newPos] = list[oldPos]
output[newPos] = input[oldPos]
if newPos < oldPos {
for i := newPos; i <= oldPos; i++ {
if i != oldPos {
newList[i+1] = list[i]
output[i+1] = input[i]
}
}
return newList
return output
}
for i := oldPos; i <= newPos; i++ {
if i != oldPos {
newList[i-1] = list[i]
output[i-1] = input[i]
}
}
return newList
return output
}
// shuffleFuncThree produces the same output as the above two functions by simply swapping
// the target element with the element one above or below in the list until that element reaches
// the desired index.
func shuffleFuncThree(list []any, oldPos, newPos int) []any {
if newPos < oldPos {
for i := oldPos; i > newPos; i-- {
list[i], list[i-1] = list[i-1], list[i]
}
return list
}
for i := oldPos; i < newPos; i++ {
list[i], list[i+1] = list[i+1], list[i]
}
return list
}

49
experiments/go/shuffle-elements/shuffle_test.go
View file

@ -39,6 +39,8 @@ var cases = []Cases{
},
}
var gout []any
func TestShuffleFuncOne(t *testing.T) {
for i := range cases {
t.Logf("Input list: %v", cases[i].list)
@ -66,3 +68,50 @@ func TestShuffleFuncTwo(t *testing.T) {
}
}
}
func TestShuffleFuncThree(t *testing.T) {
for i := range cases {
t.Logf("Input list: %v", cases[i].list)
t.Logf("We want '%v' to move to position %d", cases[i].list[cases[i].oldPosition], cases[i].newPosition)
got := shuffleFuncThree(cases[i].list, cases[i].oldPosition, cases[i].newPosition)
if !reflect.DeepEqual(cases[i].want, got) {
t.Errorf("TEST FAILED: want: %v, got %v", cases[i].want, got)
} else {
t.Logf("TEST PASSED: got %v", got)
}
}
}
func BenchmarkShuffleFuncThree(b *testing.B) {
var out []any
var benchmarkCase = []any{-183, -34, -118, -51, 161, -39, 60, -170, -15, -148, 70, 176, -101, -81, 156, -43, -130, 193, 64, 127, 49, 133, 199, -92, 178, -24, -139, 48, -171, 65, 187, -20, 124, 76, 68, -100, 43, 22, -21, 36, -46, 129, 40, 100, 171, 105, -165, 71, -192, -72, -93, -132, 34, 67, 55, -129, -41, 158, 46, 138}
for i := 0; i < b.N; i++ {
out = shuffleFuncThree(benchmarkCase, 47, 16)
}
gout = out
}
func BenchmarkShuffleFuncTwo(b *testing.B) {
var out []any
var benchmarkCase = []any{-183, -34, -118, -51, 161, -39, 60, -170, -15, -148, 70, 176, -101, -81, 156, -43, -130, 193, 64, 127, 49, 133, 199, -92, 178, -24, -139, 48, -171, 65, 187, -20, 124, 76, 68, -100, 43, 22, -21, 36, -46, 129, 40, 100, 171, 105, -165, 71, -192, -72, -93, -132, 34, 67, 55, -129, -41, 158, 46, 138}
for i := 0; i < b.N; i++ {
out = shuffleFuncTwo(benchmarkCase, 47, 16)
}
gout = out
}
func BenchmarkShuffleFuncOne(b *testing.B) {
var out []any
var benchmarkCase = []any{-183, -34, -118, -51, 161, -39, 60, -170, -15, -148, 70, 176, -101, -81, 156, -43, -130, 193, 64, 127, 49, 133, 199, -92, 178, -24, -139, 48, -171, 65, 187, -20, 124, 76, 68, -100, 43, 22, -21, 36, -46, 129, 40, 100, 171, 105, -165, 71, -192, -72, -93, -132, 34, 67, 55, -129, -41, 158, 46, 138}
for i := 0; i < b.N; i++ {
out = shuffleFuncOne(benchmarkCase, 47, 16)
}
gout = out
}