94 lines
2.5 KiB
JavaScript
94 lines
2.5 KiB
JavaScript
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(function (exports) {
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'use strict';
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function comparator(a, b) {
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return a - b;
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}
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var heapSort = (function () {
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/**
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* Finds the correct place of given element in given max heap.
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*
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* @private
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* @param {Array} array Array.
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* @param {Number} index Index of the element which palce in
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* the max heap should be found.
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* @param {Number} heapSize Size of the heap.
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* @param {function} cmp Comparison function.
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*/
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function heapify(array, index, heapSize, cmp) {
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var left = 2 * index + 1;
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var right = 2 * index + 2;
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var largest = index;
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if (left < heapSize && cmp(array[left], array[index]) > 0) {
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largest = left;
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}
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if (right < heapSize && cmp(array[right], array[largest]) > 0) {
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largest = right;
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}
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if (largest !== index) {
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var temp = array[index];
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array[index] = array[largest];
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array[largest] = temp;
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heapify(array, largest, heapSize, cmp);
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}
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}
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/**
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* Builds max heap from given array.
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*
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* @private
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* @param {Array} array Array which should be turned into max heap.
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* @param {function} cmp Comparison function.
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* @return {Array} array Array turned into max heap.
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*/
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function buildMaxHeap(array, cmp) {
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for (var i = Math.floor(array.length / 2); i >= 0; i -= 1) {
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heapify(array, i, array.length, cmp);
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}
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return array;
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}
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/**
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* Heapsort. Turns the input array into max
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* heap and after that sorts it.<br><br>
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* Time complexity: O(N log N).
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*
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* @example
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*
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* var sort = require('path-to-algorithms/src' +
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* '/sorting/heapsort').heapSort;
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* console.log(sort([2, 5, 1, 0, 4])); // [ 0, 1, 2, 4, 5 ]
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*
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* @public
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* @module sorting/heapsort
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* @param {Array} array Input array.
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* @param {Function} cmp Optional. A function that defines an
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* alternative sort order. The function should return a negative,
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* zero, or positive value, depending on the arguments.
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* @return {Array} Sorted array.
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*/
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return function (array, cmp) {
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cmp = cmp || comparator;
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var size = array.length;
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var temp;
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buildMaxHeap(array, cmp);
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for (var i = array.length - 1; i > 0; i -= 1) {
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temp = array[0];
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array[0] = array[i];
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array[i] = temp;
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size -= 1;
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heapify(array, 0, size, cmp);
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}
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return array;
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};
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}());
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exports.heapSort = heapSort;
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})(typeof window === 'undefined' ? module.exports : window);
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