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54 lines
1.7 KiB
JavaScript
54 lines
1.7 KiB
JavaScript
(function (exports) {
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'use strict';
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var binarySearch = (function () {
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/**
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* @pivate
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* @param {Array} array Array where we should find the index of the element
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* @param {Number} value Value of the element which index should be found
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* @param {Number} left Left index
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* @param {Number} right Right index
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* @returns {Number} index The index of the element or -1 if not found
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*/
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function recursiveBinarySearch(array, value, left, right) {
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if (left > right) {
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return -1;
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}
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var middle = Math.floor((right + left) / 2);
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if (array[middle] === value) {
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return middle;
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} else if (array[middle] > value) {
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return recursiveBinarySearch(array, value, left, middle - 1);
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} else {
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return recursiveBinarySearch(array, value, middle + 1, right);
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}
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}
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/**
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* Recursive version of binary search.
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* Searches for specific element in a given array using
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* the binary search algorithm.<br><br>
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* Time complexity: O(log N).
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*
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* @example
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*
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* var search = require('path-to-algorithms/src/searching/'+
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* 'recursive-binarysearch').binarySearch;
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* console.log(search([1, 2, 3, 4, 5], 4)); // 3
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*
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* @public
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* @module searching/recursive-binarysearch
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* @param {Array} array Input array.
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* @param {Number} value Value of the element which index should be found.
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* @returns {Number} Index of the element or -1 if not found.
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*/
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return function (array, value) {
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return recursiveBinarySearch(array, value, 0, array.length);
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};
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}());
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exports.binarySearch = binarySearch;
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})(typeof window === 'undefined' ? module.exports : window);
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