gds/priorityqueue_test.go at main · renaldid/gds · GitHub

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
package gds

import (
	"testing"

	"github.com/stretchr/testify/assert"
)

func TestPriorityQueue_Empty(t *testing.T) {
	pq := NewPriorityQueue(func(a, b int) bool { return a < b })
	assert.Equal(t, 0, pq.Len())
	assert.True(t, pq.IsEmpty())
}

func TestPriorityQueue_MinHeap(t *testing.T) {
	pq := NewPriorityQueue(func(a, b int) bool { return a < b })
	pq.Push(5, 1, 3, 2, 4)

	var got []int
	for !pq.IsEmpty() {
		v, ok := pq.Pop()
		assert.True(t, ok)
		got = append(got, v)
	}
	assert.Equal(t, []int{1, 2, 3, 4, 5}, got)
}

func TestPriorityQueue_MaxHeap(t *testing.T) {
	pq := NewPriorityQueue(func(a, b int) bool { return a > b })
	pq.Push(3, 1, 4, 1, 5, 9, 2, 6)

	v, _ := pq.Pop()
	assert.Equal(t, 9, v)
}

func TestPriorityQueue_Push_Single(t *testing.T) {
	pq := NewPriorityQueue(func(a, b int) bool { return a < b })
	pq.Push(42)
	assert.Equal(t, 1, pq.Len())
}

func TestPriorityQueue_Pop_Empty(t *testing.T) {
	pq := NewPriorityQueue(func(a, b int) bool { return a < b })
	v, ok := pq.Pop()
	assert.False(t, ok)
	assert.Zero(t, v)
}

func TestPriorityQueue_Pop_LastElement(t *testing.T) {
	pq := NewPriorityQueue(func(a, b int) bool { return a < b })
	pq.Push(7)
	v, ok := pq.Pop()
	assert.True(t, ok)
	assert.Equal(t, 7, v)
	assert.True(t, pq.IsEmpty())
}

func TestPriorityQueue_Peek(t *testing.T) {
	pq := NewPriorityQueue(func(a, b int) bool { return a < b })
	pq.Push(3, 1, 2)
	v, ok := pq.Peek()
	assert.True(t, ok)
	assert.Equal(t, 1, v)
	assert.Equal(t, 3, pq.Len()) // not removed
}

func TestPriorityQueue_Peek_Empty(t *testing.T) {
	pq := NewPriorityQueue(func(a, b int) bool { return a < b })
	v, ok := pq.Peek()
	assert.False(t, ok)
	assert.Zero(t, v)
}

func TestPriorityQueue_CustomType(t *testing.T) {
	type Task struct {
		Name     string
		Priority int
	}
	pq := NewPriorityQueue(func(a, b Task) bool {
		return a.Priority < b.Priority
	})
	pq.Push(Task{"low", 10}, Task{"high", 1}, Task{"mid", 5})

	v, _ := pq.Pop()
	assert.Equal(t, "high", v.Name)
}

func TestPriorityQueue_HeapProperty_AfterMultiplePops(t *testing.T) {
	pq := NewPriorityQueue(func(a, b int) bool { return a < b })
	pq.Push(10, 4, 7, 1, 8, 3)

	prev, _ := pq.Pop()
	for !pq.IsEmpty() {
		v, _ := pq.Pop()
		assert.LessOrEqual(t, prev, v)
		prev = v
	}
}