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tailscale/tempfork/heap/heap_test.go

217 lines
3.5 KiB
Go

// Copyright 2009 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
package heap
import (
"math/rand"
"testing"
"golang.org/x/exp/constraints"
)
type myHeap[T constraints.Ordered] []T
func (h *myHeap[T]) Less(i, j int) bool {
return (*h)[i] < (*h)[j]
}
func (h *myHeap[T]) Swap(i, j int) {
(*h)[i], (*h)[j] = (*h)[j], (*h)[i]
}
func (h *myHeap[T]) Len() int {
return len(*h)
}
func (h *myHeap[T]) Pop() (v T) {
*h, v = (*h)[:h.Len()-1], (*h)[h.Len()-1]
return
}
func (h *myHeap[T]) Push(v T) {
*h = append(*h, v)
}
func (h myHeap[T]) verify(t *testing.T, i int) {
t.Helper()
n := h.Len()
j1 := 2*i + 1
j2 := 2*i + 2
if j1 < n {
if h.Less(j1, i) {
t.Errorf("heap invariant invalidated [%d] = %v > [%d] = %v", i, h[i], j1, h[j1])
return
}
h.verify(t, j1)
}
if j2 < n {
if h.Less(j2, i) {
t.Errorf("heap invariant invalidated [%d] = %v > [%d] = %v", i, h[i], j1, h[j2])
return
}
h.verify(t, j2)
}
}
func TestInit0(t *testing.T) {
h := new(myHeap[int])
for i := 20; i > 0; i-- {
h.Push(0) // all elements are the same
}
Init[int](h)
h.verify(t, 0)
for i := 1; h.Len() > 0; i++ {
x := Pop[int](h)
h.verify(t, 0)
if x != 0 {
t.Errorf("%d.th pop got %d; want %d", i, x, 0)
}
}
}
func TestInit1(t *testing.T) {
h := new(myHeap[int])
for i := 20; i > 0; i-- {
h.Push(i) // all elements are different
}
Init[int](h)
h.verify(t, 0)
for i := 1; h.Len() > 0; i++ {
x := Pop[int](h)
h.verify(t, 0)
if x != i {
t.Errorf("%d.th pop got %d; want %d", i, x, i)
}
}
}
func Test(t *testing.T) {
h := new(myHeap[int])
h.verify(t, 0)
for i := 20; i > 10; i-- {
h.Push(i)
}
Init[int](h)
h.verify(t, 0)
for i := 10; i > 0; i-- {
Push[int](h, i)
h.verify(t, 0)
}
for i := 1; h.Len() > 0; i++ {
x := Pop[int](h)
if i < 20 {
Push[int](h, 20+i)
}
h.verify(t, 0)
if x != i {
t.Errorf("%d.th pop got %d; want %d", i, x, i)
}
}
}
func TestRemove0(t *testing.T) {
h := new(myHeap[int])
for i := 0; i < 10; i++ {
h.Push(i)
}
h.verify(t, 0)
for h.Len() > 0 {
i := h.Len() - 1
x := Remove[int](h, i)
if x != i {
t.Errorf("Remove(%d) got %d; want %d", i, x, i)
}
h.verify(t, 0)
}
}
func TestRemove1(t *testing.T) {
h := new(myHeap[int])
for i := 0; i < 10; i++ {
h.Push(i)
}
h.verify(t, 0)
for i := 0; h.Len() > 0; i++ {
x := Remove[int](h, 0)
if x != i {
t.Errorf("Remove(0) got %d; want %d", x, i)
}
h.verify(t, 0)
}
}
func TestRemove2(t *testing.T) {
N := 10
h := new(myHeap[int])
for i := 0; i < N; i++ {
h.Push(i)
}
h.verify(t, 0)
m := make(map[int]bool)
for h.Len() > 0 {
m[Remove[int](h, (h.Len()-1)/2)] = true
h.verify(t, 0)
}
if len(m) != N {
t.Errorf("len(m) = %d; want %d", len(m), N)
}
for i := 0; i < len(m); i++ {
if !m[i] {
t.Errorf("m[%d] doesn't exist", i)
}
}
}
func BenchmarkDup(b *testing.B) {
const n = 10000
h := make(myHeap[int], 0, n)
for i := 0; i < b.N; i++ {
for j := 0; j < n; j++ {
Push[int](&h, 0) // all elements are the same
}
for h.Len() > 0 {
Pop[int](&h)
}
}
}
func TestFix(t *testing.T) {
h := new(myHeap[int])
h.verify(t, 0)
for i := 200; i > 0; i -= 10 {
Push[int](h, i)
}
h.verify(t, 0)
if (*h)[0] != 10 {
t.Fatalf("Expected head to be 10, was %d", (*h)[0])
}
(*h)[0] = 210
Fix[int](h, 0)
h.verify(t, 0)
for i := 100; i > 0; i-- {
elem := rand.Intn(h.Len())
if i&1 == 0 {
(*h)[elem] *= 2
} else {
(*h)[elem] /= 2
}
Fix[int](h, elem)
h.verify(t, 0)
}
}