Nodejs Array Search Binary binaryIndexOfbinaryIndexOf;

Method Source Code

function binaryIndexOf(searchElement, map) {
   'use strict';//w w  w  .  j  a  va2 s . co  m

   if (map === undefined) map = index => this[index]

   var minIndex = 0;
   var maxIndex = this.length - 1;
   var currentIndex;
   var currentElement;
   var resultIndex;

   while (minIndex <= maxIndex) {
      resultIndex = currentIndex = (minIndex + maxIndex) / 2 | 0;
      currentElement = map(currentIndex);

      if (currentElement < searchElement) {
         minIndex = currentIndex + 1;
      }
      else if (currentElement > searchElement) {
         maxIndex = currentIndex - 1;
      }
      else {
         return currentIndex;
      }
   }

   return ~maxIndex;
}

Array.prototype.binaryIndexOf = binaryIndexOf;

Related

1. binSearch(data)

   Array.prototype.binSearch = function(data) {
     var first = 0;
     var last = this.length - 1;
     while(first <= last) {
       var mid = Math.floor((first + last) / 2);
       if(this[mid] < data) {
         first = mid + 1;
       else if(this[mid] > data) {
   ...
   

2. binaryIndexOf(searchElement)

   function binaryIndexOf(){
   Array.prototype.binaryIndexOf = function(searchElement) {
       var minIndex = 0;
       var maxIndex = this.length - 1;
       var currentIndex;
       var currentElement;
       while (minIndex <= maxIndex) {
           currentIndex = Math.floor((minIndex + maxIndex) / 2);
           currentElement = this[currentIndex];
   ...
   

3. 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));
     });
   });
   

4. 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);
   ...
   

5. 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];
   ...
   

6. 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) {
   ...