Heap sort
JavaScript, Algorithm, Array, Recursion · Dec 28, 2020
Sorts an array of numbers, using the heapsort algorithm.
- Use recursion.
- Use the spread operator (
...) to clone the original array,arr. - Use closures to declare a variable,
l, and a functionheapify. - Use a
forloop andMath.floor()in combination withheapifyto create a max heap from the array. - Use a
forloop to repeatedly narrow down the considered range, usingheapifyand swapping values as necessary in order to sort the cloned array.
const heapsort = arr => {
const a = [...arr];
let l = a.length;
const heapify = (a, i) => {
const left = 2 * i + 1;
const right = 2 * i + 2;
let max = i;
if (left < l && a[left] > a[max]) max = left;
if (right < l && a[right] > a[max]) max = right;
if (max !== i) {
[a[max], a[i]] = [a[i], a[max]];
heapify(a, max);
}
};
for (let i = Math.floor(l / 2); i >= 0; i -= 1) heapify(a, i);
for (i = a.length - 1; i > 0; i--) {
[a[0], a[i]] = [a[i], a[0]];
l--;
heapify(a, 0);
}
return a;
};heapsort([6, 3, 4, 1]); // [1, 3, 4, 6]Written by Angelos Chalaris
I'm Angelos Chalaris, a JavaScript software engineer, based in Athens, Greece. The best snippets from my coding adventures are published here to help others learn to code.
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