heap-data-structure/d-ary-heap

import siftdown from './siftdown.js';

/**
 * Pops the root from a d-ary heap.
 *
 * Hypothesis : i < j
 *
 * @param {int} arity arity of the heap
 * @param {function} compare the comparison function
 * @param {function} swap the swap function
 * @param {array} a the array where the heap is stored
 * @param {int} i is the root
 * @param {int} j - 1 is the last leaf
 */

export default function pop(arity, compare, swap, a, i, j) {
    // Decrement size of heap

    --j;

    // Put last leaf at root

    const popped = a[i];
    a[i] = a[j];

    // Sift down the new root

    siftdown(arity, compare, swap, a, i, j, i);

    // Return old root

    return popped;
}