javascript - Khan academy Algorithm: Binary Search Solution -


i working towards algorithms in khan academy : https://www.khanacademy.org/computing/computer-science/algorithms/binary-search/p/challenge-binary-search of code below results in -1 ? why that? binary search wont work efficiently ? 

    var dosearch = function(array, targetvalue) {     var min = 0;     var max = array.length - 1;     var guess;      while(min < max) {         guess = math.floor((max + min) / 2);          if (array[guess] === targetvalue) {             return guess;         }         else if (array[guess] < targetvalue) {             min = guess + 1;         }         else {             max = guess - 1;         }      }      return -1; };  var primes = [2, 3, 5, 7, 11, 13, 17, 19, 23, 29, 31, 37,          41, 43, 47, 53, 59, 61, 67, 71, 73, 79, 83, 89, 97];  for(var i=0;i<primes.length;i++){     var result = dosearch(primes,primes[i]);     console.log("found prime @ index of " + primes[i] +" @ " + result);     }

results:

found prime @ index of 2 @ 0 found prime @ index of 3 @ -1 found prime @ index of 5 @ 2 found prime @ index of 7 @ 3 found prime @ index of 11 @ -1 found prime @ index of 13 @ 5 found prime @ index of 17 @ 6 found prime @ index of 19 @ -1 found prime @ index of 23 @ 8 found prime @ index of 29 @ -1 found prime @ index of 31 @ 10 found prime @ index of 37 @ -1 found prime @ index of 41 @ 12 found prime @ index of 43 @ 13 found prime @ index of 47 @ -1 found prime @ index of 53 @ 15 found prime @ index of 59 @ 16 found prime @ index of 61 @ -1 found prime @ index of 67 @ 18 found prime @ index of 71 @ 19 found prime @ index of 73 @ -1 found prime @ index of 79 @ 21 found prime @ index of 83 @ -1 found prime @ index of 89 @ 23 found prime @ index of 97 @ -1

what missing?

you terminating loop - min == max valid condition.

change loop 

while(min <= max) {     guess = math.floor((max + min) / 2);      if (array[guess] === targetvalue) {         return guess;     }     else if (array[guess] < targetvalue) {         min = guess + 1;     }     else {         max = guess - 1;     }  }

i output of 

vm153:30 found prime @ index of 2 @ 0 vm153:30 found prime @ index of 3 @ 1 vm153:30 found prime @ index of 5 @ 2 vm153:30 found prime @ index of 7 @ 3 vm153:30 found prime @ index of 11 @ 4 vm153:30 found prime @ index of 13 @ 5 vm153:30 found prime @ index of 17 @ 6 vm153:30 found prime @ index of 19 @ 7 vm153:30 found prime @ index of 23 @ 8 vm153:30 found prime @ index of 29 @ 9 vm153:30 found prime @ index of 31 @ 10 vm153:30 found prime @ index of 37 @ 11 vm153:30 found prime @ index of 41 @ 12 vm153:30 found prime @ index of 43 @ 13 vm153:30 found prime @ index of 47 @ 14 vm153:30 found prime @ index of 53 @ 15 vm153:30 found prime @ index of 59 @ 16 vm153:30 found prime @ index of 61 @ 17 vm153:30 found prime @ index of 67 @ 18 vm153:30 found prime @ index of 71 @ 19 vm153:30 found prime @ index of 73 @ 20 vm153:30 found prime @ index of 79 @ 21 vm153:30 found prime @ index of 83 @ 22 vm153:30 found prime @ index of 89 @ 23 vm153:30 found prime @ index of 97 @ 24

Comments

Post a Comment

Popular posts from this blog

angularjs - ADAL JS Angular- WebAPI add a new role claim to the token -

i have created angular spa webapi backend using adal js authentication.as there no roles in ad, need manually add role claims in order give users access different api controllers. the roles stored in database. expecting inject claim through call webapi after authentication ad. webapi code might this. identity.addclaim(new claim("role", "user")); var ticket = new authenticationticket(identity, props); var accesstoken = startup.oauthbeareroptions.accesstokenformat.protect(ticket); is possible replace adal idtoken new token? is viable solution or there other better way handle this? as initial token generated azuread, possible edit token add new claim? appreciated. graph api supporting group claims. see here: http://justazure.com/azure-active-directory-part-4-group-claims/ if @ examples on page, users assigned groups , app can check group in claims. in current version of portal, need app manifest , modify it.
Read more

node.js - Using Node without global install -

i'm working on few node & electron (atom shell) projects , i'm curious how them work without user having install node globally. i've seen few applications including node directory in project contains node.exe binary. how go setting node project use binary? edit: thought should add, i've searched everywhere answer this, unrelated results.
Read more

php - CakePHP HttpSockets send array of paramms -

i problem when make request (i can request). $link = 'http://uri/path/?param1=1&sid=2&sid=3&sid=4' $http = $httpsocket = new httpsocket(); $res = $httpsocket->get($link); if check request pr($http); i see : [line] => /url/path/?param1=1&sid%5b0%5d=2&sid%5b1%5d=3&sid%5b2%5d=4 http/1.1 and i'm getting empty response because server doesn't know parameters sid%5b0%5d=2 when try send parameters array : $data = array('param1' => '1', 'sid' => array('2','3', '4')); i see same changes %5b0%5d - additional indexes. how fix it? unfortunately , can not change server side, if send request in browser, i'll normal response in json format. when make request, can parameters this: $param1 = $_get['param1']; $sid= $_get['sid']; tip: use diferente names parameters. have multiples sid. use sid1, sid2, sid3... update: can parameters this:...
Read more