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Commit 4fb0809

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merge: fixes: #774 - add test and fix MinPriorityQueue implementation (#811)
1 parent 32781c2 commit 4fb0809

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2 files changed

+50
-16
lines changed

2 files changed

+50
-16
lines changed

‎Data-Structures/Heap/MinPriorityQueue.js

Lines changed: 24 additions & 9 deletions
Original file line numberDiff line numberDiff line change
@@ -57,13 +57,22 @@ class MinPriorityQueue {
5757
output(this.heap.slice(1))
5858
}
5959

60-
// heap sorting can be done by performing
61-
// delete function to the number of times of the size of the heap
62-
// it returns reverse sort because it is a min priority queue
63-
heapSort () {
64-
for (let i = 1; i < this.capacity; i++) {
65-
this.delete()
60+
// heap reverse can be done by performing swaping the first
61+
// element with the last, removing the last element to
62+
// new array and calling sink function.
63+
heapReverse () {
64+
const heapSort = []
65+
while (this.size > 0) {
66+
// swap first element with last element
67+
[this.heap[1], this.heap[this.size]] = [this.heap[this.size], this.heap[1]]
68+
heapSort.push(this.heap.pop())
69+
this.size--
70+
this.sink()
6671
}
72+
// first value from heap it's empty to respect
73+
// structure with 1 as index of the first element
74+
this.heap = [undefined, ...heapSort.reverse()]
75+
this.size = heapSort.length
6776
}
6877

6978
// this function reorders the heap after every delete function
@@ -98,11 +107,17 @@ class MinPriorityQueue {
98107
}
99108
}
100109

101-
// deletes the highest priority value from the heap
110+
// deletes the highest priority value from the heap. The last
111+
// element goes to ahead to first position and reorder heap
102112
delete () {
113+
// checks empty and one element array conditions
114+
if (this.isEmpty()) return
115+
if (this.size === 1) {
116+
this.size--
117+
return this.heap.pop()
118+
}
103119
const min = this.heap[1]
104-
this.heap[1] = this.heap[this.size]
105-
this.heap[this.size] = min
120+
this.heap[1] = this.heap.pop()
106121
this.size--
107122
this.sink()
108123
return min

‎Data-Structures/Heap/test/MinPriorityQueue.test.js

Lines changed: 26 additions & 7 deletions
Original file line numberDiff line numberDiff line change
@@ -3,14 +3,16 @@ import { MinPriorityQueue } from '../MinPriorityQueue'
33
describe('MinPriorityQueue', () => {
44
const values = [5, 2, 4, 1, 7, 6, 3, 8]
55
const capacity = values.length
6+
let queue
67

7-
const Queue = new MinPriorityQueue(capacity)
8-
9-
values.forEach(v => Queue.insert(v))
8+
beforeEach(() => {
9+
queue = new MinPriorityQueue(capacity)
10+
values.forEach(v => queue.insert(v))
11+
})
1012

1113
it('Check heap ordering', () => {
1214
const mockFn = jest.fn()
13-
Queue.print(mockFn)
15+
queue.print(mockFn)
1416

1517
expect(mockFn.mock.calls.length).toBe(1) // Expect one call
1618
expect(mockFn.mock.calls[0].length).toBe(1) // Expect one argument
@@ -21,10 +23,9 @@ describe('MinPriorityQueue', () => {
2123
})
2224

2325
it('heapSort() expected to reverse the heap ordering', () => {
24-
Queue.heapSort()
25-
26+
queue.heapReverse()
2627
const mockFn = jest.fn()
27-
Queue.print(mockFn)
28+
queue.print(mockFn)
2829

2930
expect(mockFn.mock.calls.length).toBe(1)
3031
expect(mockFn.mock.calls[0].length).toBe(1)
@@ -33,4 +34,22 @@ describe('MinPriorityQueue', () => {
3334
expect(heap.length).toBe(capacity)
3435
expect(heap).toStrictEqual([8, 7, 6, 5, 4, 3, 2, 1])
3536
})
37+
38+
describe('delete() function work properly', () => {
39+
it('return undefined if heap is empty', () => {
40+
const minqueue = new MinPriorityQueue(capacity)
41+
const min = minqueue.delete()
42+
expect(min).toBe(undefined)
43+
})
44+
it('return min value and remove it', () => {
45+
const sortedValues = values.sort()
46+
let initialSize = queue.size
47+
sortedValues.forEach((minValue, index) => {
48+
const min = queue.delete()
49+
expect(min).toBe(minValue)
50+
expect(queue.size).toBe(--initialSize)
51+
})
52+
expect(queue.size).toBe(0)
53+
})
54+
})
3655
})

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