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Commit d79eb7a

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add heap extract method for min & max heaps, which returns the extracted node. + tests
1 parent e5e2a43 commit d79eb7a

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7 files changed

+1099
-11
lines changed

7 files changed

+1099
-11
lines changed

‎babel.config.js

Lines changed: 6 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -0,0 +1,6 @@
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module.exports = {
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presets: [
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['@babel/preset-env', {targets: {node: 'current'}}],
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'@babel/preset-typescript',
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],
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};

‎dist/datastructures/BinaryHeap.js

Lines changed: 51 additions & 2 deletions
Original file line numberDiff line numberDiff line change
@@ -1,24 +1,73 @@
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"use strict";
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Object.defineProperty(exports, "__esModule", { value: true });
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class BinaryHeap {
4-
constructor(type) {
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constructor(type,initialValues) {
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this.values = [];
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this.type = type;
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if (initialValues) {
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initialValues.forEach((value) => this.insert(value));
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}
710
}
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insert(value) {
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// recursive insert implementation, returns the heap with the value inserted
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this.values.push(value);
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let valueIndex = this.values.length - 1;
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const helper = () => {
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let parentIndex = Math.floor((valueIndex - 1) / 2);
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if (this.type === 'max' && this.values[parentIndex] < value
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|| this.type === 'min' && this.values[parentIndex] > value) {
15-
[this.values[valueIndex], this.values[parentIndex]] = [this.values[parentIndex], this.values[valueIndex]]; // swap parent and larger child
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[this.values[valueIndex], this.values[parentIndex]] = [this.values[parentIndex], this.values[valueIndex]]; // swap parent and child
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valueIndex = parentIndex;
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helper();
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}
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};
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helper();
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return this.values;
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}
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extract() {
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// badly in need of a refactor
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if (!this.values.length)
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return;
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const newRoot = this.values.pop();
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const extractedNode = this.values[0];
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this.values[0] = newRoot;
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let nodeIndex = 0;
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if (this.type === 'max' && this.values[0] > Math.max(this.values[1], this.values[2]) || this.type === 'min' && this.values[0] < Math.min(this.values[1], this.values[2]))
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return extractedNode;
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const helper = () => {
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let children = { left: [this.values[nodeIndex * 2 + 1], nodeIndex * 2 + 1], right: [this.values[nodeIndex * 2 + 2], nodeIndex * 2 + 2] };
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if (nodeIndex * 2 + 1 >= this.values.length)
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return;
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if (this.type === 'max') {
42+
if ((children.left[0] <= this.values[nodeIndex] || children.left[0] === undefined) && (children.right[0] <= this.values[nodeIndex] || children.right[0] === undefined))
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return;
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if (children.left[0] > children.right[0]) {
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[this.values[nodeIndex], this.values[children.left[1]]] = [this.values[children.left[1]], this.values[nodeIndex]]; // swap
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nodeIndex = children.left[1];
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}
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else {
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[this.values[nodeIndex], this.values[children.right[1]]] = [this.values[children.right[1]], this.values[nodeIndex]]; // swap
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nodeIndex = children.right[1];
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}
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}
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else if (this.type === 'min') {
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if ((children.left[0] >= this.values[nodeIndex] || children.left[0] === undefined) && (children.right[0] >= this.values[nodeIndex] || children.right[0] === undefined))
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return;
56+
if (children.left[0] < children.right[0]) {
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[this.values[nodeIndex], this.values[children.left[1]]] = [this.values[children.left[1]], this.values[nodeIndex]]; // swap
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nodeIndex = children.left[1];
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}
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else {
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[this.values[nodeIndex], this.values[children.right[1]]] = [this.values[children.right[1]], this.values[nodeIndex]]; // swap
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nodeIndex = children.right[1];
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}
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}
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helper(); // recurse
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};
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helper();
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return extractedNode;
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}
2370
}
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// if ((this.type === 'max' && children.left[0] <= this.values[nodeIndex]) && (children.right[0] <= this.values[nodeIndex])) return;
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exports.default = BinaryHeap;
73+
// if (nodeIndex * 2 + 1 >= this.values.length || (this.type === 'max' && children.left[0] <= this.values[nodeIndex]) && (children.right[0] <= this.values[nodeIndex]) || (this.type === 'min' && children.left[0] >= this.values[nodeIndex]) && (children.right[0] >= this.values[nodeIndex]))

‎dist/datastructures/BinaryHeap.test.js

Lines changed: 18 additions & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -57,7 +57,24 @@ describe('min binary heap insert method tests', () => {
5757
MinBH.insert(20);
5858
MinBH.insert(1);
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MinBH.insert(0);
60-
console.log(MinBH.values);
6160
expect(MinBH.values).toEqual([0, 1, 25, 20, 90, 95, 80, 100, 85]);
6261
});
62+
test('can initialize a binary heap with an array of values, which it will insert into binary heap format', () => {
63+
MaxBH = new BinaryHeap_1.default('max', [1, 2, 3, 100]);
64+
MinBH = new BinaryHeap_1.default('min', [1, 2, 3, 100]);
65+
expect(MaxBH.values).toEqual([100, 3, 2, 1]);
66+
expect(MinBH.values).toEqual([1, 2, 3, 100]);
67+
});
68+
test('max: can extract root node and heap will sink down a new root node from the end, and end up with a heap with proper form', () => {
69+
MaxBH = new BinaryHeap_1.default('max', [100, 200, 300, 400, 500]);
70+
const extractedMaxNode = MaxBH.extract();
71+
expect(extractedMaxNode).toBe(500);
72+
expect(MaxBH.values).toEqual([400, 300, 200, 100]);
73+
});
74+
test('min: can extract root node and heap will sink down a new root node from the end, and end up with a heap with proper form', () => {
75+
MinBH = new BinaryHeap_1.default('min', [500, 400, 300, 200, 100]);
76+
const extractedMinNode = MinBH.extract();
77+
expect(extractedMinNode).toBe(100);
78+
expect(MinBH.values).toEqual([200, 300, 400, 500]);
79+
});
6380
});

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