Nodejs Array Search Binary binarySearch(value)

Method Source Code

Array.prototype.binarySearch = function(value) {
    'use strict';

    if(!value){// ww w.  j  a  v a2 s  .c o m
        return null;
    }

    var left = 0,
        right = this.length-1,
        find = false,
        middle = null;

    while( left <= right && !find ){
        middle = parseInt(left+(right-left)/2);
        
        if(this[middle]<value){
            left = middle + 1;
        } else  if(this[middle] > value){
            right = middle -1;
        } else {
            find = true;
        }
    }

    if(find){
        return middle;
    } else {
        return false;
    }
};

var vector = [1, 2, 3, 5, 6, 7, 9, 82];

console.log(vector);

console.log(vector.binarySearch(7));

Related

1. binarySearch(n)

   "use strict";
   var assert = require('assert'); 
   Array.prototype.binarySearch = function(n) {
     var O = Object(this);
     var f = function(lo,hi) {
       var mid = Math.floor((lo + hi) / 2);
       if (O[mid] === n) {
         return mid;
       if (lo === mid || hi === mid) {
         return -(mid+1);
       if(O[mid] < n) {
         return f(mid,hi);
       if (O[mid] > n) {
         return f(lo,mid);
     };
     return f(0, O.length);
   };
   describe('binary search', function() {
     it('doesnt find anything in an empty list', function() {
       assert.equal(-1, [].binarySearch(7));
     });
     it('finds a single element', function() {
       assert.equal(0, [0].binarySearch(0));
     });
     it('finds the middle element', function() {
       assert.equal(1, [1,2,3].binarySearch(2));
     });
     it('finds up', function() {
       assert.equal(2, [1,2,3].binarySearch(3));
     });
     it('finds down', function() {
       assert.equal(0, [1,2,3].binarySearch(1));
     });
     it('finds insertion index', function() {
       assert.equal(-2, [1,2,4,5,6].binarySearch(3));
     });
   });
   

2. binarySearch(num)

   var input = [ 1, 2, 2, 3, 4, 4, 5, 6, 8, 10 ];
   Array.prototype.binarySearch = function(num) {
       var _this = this;
       function search(left, right) {
           if(right < left) return -1;
           else if(left === right) {
               return checkIndexForNum(left);
           var mid = Math.floor((left + right) / 2);
   ...
   

3. binarySearch(searchElement)

   Array.prototype.binarySearch = function (searchElement) {
       'use strict';
       var minIndex = 0;
       var maxIndex = this.length - 1;
       var currentIndex;
       var currentElement;
       while (minIndex <= maxIndex) {
           currentIndex = (minIndex + maxIndex) / 2 | 0;
           currentElement = this[currentIndex];
   ...
   

4. binarySearch(val)

   Array.prototype.binarySearch = function(val){
     var min = 0;
     var max = this.length -1;
     var currentIndex;
     var currentElement;
     while (min <= max) {
       currentIndex = Math.floor((min +max) / 2);
       currentElement = this[currentIndex];
       if (currentElement > val) {
   ...
   

5. binarySearch(val)

   Array.prototype.binarySearch = function(val){
     var keeper = 0;
     var answer = -1;
     function recursive(arr){
       var len = arr.length;
       var start = Math.floor(len / 2);
       var current = arr[start];
       if (current === val){
         answer = start + keeper;
   ...
   

6. binarySearch(value)

   Array.prototype.binarySearch = function(value){
       var items = this;
       console.log(items.length);
       var startIndex  = 0;
       var stopIndex = items.length - 1;
       var middle = Math.floor((stopIndex + startIndex)/2);
       while(items[middle] != value && startIndex < stopIndex){
           if (value < items[middle]){
               stopIndex = middle - 1;
   ...
   

7. binarySearchbinaryIndexOf;

   function binaryIndexOf(searchElement) {
       'use strict';
       var minIndex = 0;
       var maxIndex = this.length - 1;
       var currentIndex = -1;
       var currentElement;
       while (minIndex <= maxIndex) {
           currentIndex = (minIndex + maxIndex) / 2 | 0;
           currentElement = this[currentIndex];
   ...
   

8. binarySearchbinarySearch(val, from, to)

   Array.prototype.binarySearch = function binarySearch(val, from, to){
       if (from === undefined) {
           from = 0;
       if (to === undefined) {
           to = this.length-1;
       var mid = Math.ceil((from+to)/2),
           midVal = this[mid];
   ...
   

9. binary_search(val, left, right)

   Array.prototype.binary_search = function(val, left, right) {
       if (typeof left === 'undefined') left = 0;
       if (typeof right === 'undefined') right = this.length - 1;
       if (left > right) return null;
       var mid = (left + right) >> 1;
       if (val == this[mid]) {
           return mid;
       } else if (val > this[mid]) {
           return this.binary_search(val, mid + 1, right);
   ...