Largest Binary Gap (JavaScript)

largestBinaryGap.js

function largestBinaryGap(num) {
  var bin = Math.abs(num).toString(2),
      finalMax = 0,
      currentMax;
  
  for (var i = 0; i < bin.length; i++) {
    currentMax = 0;
    while (bin[i] === "0") {
      ++currentMax && ++i;
    }
    finalMax = Math.max(finalMax, currentMax);
  }
  return finalMax;
}

console.log(largestBinaryGap(1)); // 1 //=> 0
console.log(largestBinaryGap(5)); // 101 //=> 1
console.log(largestBinaryGap(6)); // 110 //=> 1
console.log(largestBinaryGap(19)); // 10011 //=> 2
console.log(largestBinaryGap(1041)); // 10000010001 //=> 5
console.log(largestBinaryGap(6291457)); // 11000000000000000000001 //=> 20
console.log(largestBinaryGap(1376796946)); // 1010010000100000100000100010010 //=> 5
console.log(largestBinaryGap(1610612737)); // 1100000000000000000000000000001 //=> 28

function mindTheGap(n) {
  const str = n.toString(2)
  const substr = str.substring(0, str.lastIndexOf('1'))
  const split = substr.split('1')  
  return split.sort().reverse()[0].length
}

Even better;

function solution(N) {
    const binary = N.toString(2)
    const splitedZeros = binary.substring(0, binary.lastIndexOf('1')).replace(/^1/, '').split('1');
    return Math.max(...(splitedZeros.map(el => el.length)))
}

Nice to read and understand:

function solution(N) {
    return N
      .toString(2)
      .replace(/[0]*$/, '')
      .split('1')
      .reduce((acc, a) =>
        a.length > acc ? a.length : acc
      , 0);
}

This is a very correct function that passed all test cases.

function solution(N) { // write your code in JavaScript (Node.js 8.9.4) let bin = (N >>> 0).toString(2); let binarr = bin.split('1'); let count_arr = []; for (let i = 0; i < binarr.length; i++) { if (i == 0 || i == binarr.length - 1) continue; else{ count_arr.push(binarr[i].length); } }; // console.log(count_arr); // console.log(Math.max( ...count_arr )); if (count_arr.length == 0){ return 0; }else{ return Math.max( ...count_arr ); } }

This is my example. Test Results Score 86% in Codility

function solution(N) {
    // write your code in JavaScript (Node.js 8.9.4)
    if(N.toString(2).match(/1[0]*1/)) {
        return N.toString(2).split("1").sort((x,y) => {return y.length-x.length})[0].length;
    } else return 0;
}

This is my example. Test Results Score 100% in Codility

solution = (N) => {
 var a = N.toString(2).split('');
 //console.log(a)
 var max = 0;
 var count = 0;
 for(var i = 0; i < a.length; i++) {
    //console.log(max, count)
      if (a[i] == 1 && a[i+1] == 0 || (count > 0 && a[i] == 0 && a[i+1] == 1)) {
         max = Math.max(max, count);
         count = 1;
      } else if (count > 0 && a[i] == 0 && a[i+1] == 0) {
         count++; 
      } 
 }
 return max;
}

//life is simple dont let any one give you a complex code to learn
//just read between the lines and understand the question

//given N
const given = N;
let noZeroes = false; // task is to loop to count zeroes before a 1 right?
const bin = N.toString(2) // needed
//console.log(bin)
let counter =0; // the counter
let jackPot = []; // yeah did it get me a 1
let binArr = bin.split("") // convert the bin to array so we can loop the hell out of it

const resetCounter = function(){counter =0 ; } // yeah i need to reset count to 0 when i hit a 1 so i can count for other 0's before the next 1

for(let i=0; i<binArr.length; i++){ // the looping hell master
  if(parseInt(binArr[i])==0){ // of course you get this point
      counter++
      noZeroes = false;
  }else if(binArr[i]==1 && counter>0){ // here we make sure that our count is > 0
      jackPot.push(counter) // hmmm
      resetCounter() // ahuh
      noZeroes = false; //woop me
      
  }  else{
      noZeroes==true // finally just incase we dont see a 1 again 
      
  }  
   
}


//console.log(jackPot)
if(jackPot.length>0){
    const max = Math.max( ...jackPot);
//  console.log(max)
  return parseInt(max) 
}
return 0

//gracias

}

I got 100% with this code.

function solution(N) {
    let binary = parseInt(N).toString(2);
    let remove_last_zero = binary.slice(0, binary.lastIndexOf("1") + 1);
    let split_1 = remove_last_zero.split("1");
    let remove_empty = split_1.filter(i => i != "");
    if (typeof remove_empty !== 'undefined' && remove_empty.length == 0) {
        return 0;
    }
    let zero_count = remove_empty.map(b => b.length);
    return Math.max.apply(null, zero_count);
}

I did it like this

`function solution(N) {
const binary = N.toString(2)
let finalMax = 0, currentMax = 0

for(let i = 0; i < binary.length; i++) {
if(binary[i] == 1) {
i++
while(binary[i] == 0 && i < binary.length) {
currentMax++
i++
}
if (i == binary.length && binary[i] != 1) {
currentMax = 0
}
if(finalMax < currentMax) {
finalMax = currentMax
currentMax = 0
}
i--
}
currentMax = 0
}
return finalMax
}`

I actually used this approach. How more ugly could it be? lol
function solution(N){
return Math.max(...countZeroesLengthInArray(splitNum(ignoreZeroesAfterLastOne(changeToBin(N)))))
}

const changeToBin = (num) => {
const toChange = num;
return toChange.toString(2);
}

const ignoreZeroesAfterLastOne = (numInString) => {
return numInString.slice(0, numInString.lastIndexOf("1") + 1);
}

const splitNum = (num) => {
return num.split("1");
}

const countZeroesLengthInArray = (arr) => {
return arr.map((curr) => {
return curr.length;
},0);
}

I never saw so many solutions, which are kind of missing the point. Well actually the solution to transform to a "binary" string and splitting is actually funny, but I think most of you are just writing garbage.

The point of the task is to write the most efficient way to calculate the binary gap. This means to use less memory (=> use as less variables as possible), use less branching and use less calculations as possible.

My Solution:

function solution(N) {

    let start = null;
    let max = 0;

    for (let pos = 31; pos >= 0; pos--) {
        if ((N >> pos & 1) === 1) {
            if (start === null) {
                start = pos;
            } else {
                max = max < (start - pos) ? start - pos - 1 : max;
                start = pos;
            }
        }
    }

    return max;
}

Or even less by doing less subtractions:

function solution(N) {

    let start = null;
    let max = 1;

    for (let pos = 31; pos >= 0; pos--) {
        if ((N >> pos & 1) === 1) {
            if (start === null) {
                start = pos;
            } else {
                max = max < (start - pos ) ? start - pos : max;
                start = pos;
            }
        }
    }

    return --max;
}

Further improvements could be e.g. to first ignore all 0 at the beginning with a while loop and set the start then go through the for loop avoiding the branching if (start === null).

But really guys... some should be ashamed...

function solution(N) {
    const number = N.toString(2)
    let max = 0;
    let currentMax = 0;
    for (let index = 0; index < number.length; index++) {
      if (number[index] === "0") currentMax++
      if (number[index] === "1") {
        max = Math.max(currentMax, max)
        currentMax = 0
      }
    }
    return max
}

The easiest solution

function solution(N) {
  return N.toString(2)
    .split("1")
    .slice(1, -1)
    .reduce((a, b) => (a > b.length ? a : b.length), 0);
}

Simple solution with 100% score:

function solution(N) {
  let newN = N.toString(2);
  let max = current = 0;
  for (char of newN) {
    if (char == "1") {
      max = Math.max(current, max);
      current = 0;
    } else {
      current++;
    }
  }
  return max;
}

 function solution(N) {
  return N.toString(2)
    .split("1")
    .slice(1, -1)
    .reduce((a, b) => (a > b.length ? a : b.length), 0);
}

This was the one that made the most sense to me and helped debug my own code, thank you so much!

After reading all these solutions, I came up with something that beginners can really easily understand:

const highestBinaryGap = (n)  => {
    let binary_number = n.toString(2)
    splited_binary_number = binary_number.toString().split("1")
    let maxCharacterArray = []
    for (let i = 0; i < splited_binary_number.length; i++) {
        if (splited_binary_number[i] !== "") {
            let length = splited_binary_number[i].length
            maxCharacterArray.push(length)
        }
    }
    let theHigestOccurance = Math.max(...maxCharacterArray)
    return theHigestOccurance
}
// Usage
theHigestBinaryGap = highestBinaryGap(593)
console.log(theHigestBinaryGap)

This is my solution with very less code and no direct loops

  function solution(N) {
      const binnum = Number(N).toString(2);
      let str = binnum.split('1');
      const newarr = str.filter(function(item,index){
          if (item === ''){
          }else if (index === str.length -1) {
          }else {
              return item;
          }
      })
      return newarr.length > 0 ? newarr.sort()[newarr.length -1].length : 0;
  }