Dutch national flag problem in Javascript

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Dutch national flag problem and solution in Javascript Problem statement:   The Dutch national flag (DNF) problem is one of the most popular programming problems proposed by Edsger Dijkstra. The flag of the Netherlands consists of three colors: white, red, and blue. The task is to randomly arrange balls of white, red, and blue such that balls of the same color are placed together. Now, let's consider an array with 3 distinct values say 0, 1 and 2. We won't be using any sort method and we need to sort this array in 0(n). Input Array :  let   arr  = [ 0 ,  2 ,  1 ,  0 ,  1 ,  2 ,  0 ,  2 ]; Expected Output: [ 0, 0, 0, 1, 1, 2, 2, 2 ] Solution Approach : When we see expected output, we can clearly see that sorted array is divided into 3 sections having values 0 , 1 and 2. So, let's divide the array in 3 sections: a) from 0th index to left boundary b) from left boundary to right boundary c) from right boundary to last index. Now we will create 2 pointers : left (starting from 0
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Javascript Codewars Problem: "Highest Rank Number in an Array"

 Codewars Problem and solution in Javascript

Objective: 

In this challenge, we will solve the “Highest Rank Number in an Array” Codewars Kata using javascript. 

Problem statement: 

Complete the method which returns the number which is most frequent in the given input array. If there is a tie for most frequent number, return the largest number among them. 


Examples: 

Input : [12, 10, 8, 12, 7, 6, 4, 10, 12]

Output : 12


Input :  [12, 10, 8, 12, 7, 6, 4, 10, 12, 10]

Output:  12


Input : [12, 10, 8, 8, 3, 3, 3, 3, 2, 4, 10, 12, 10]

Output : 3




Solution Approach: 

we will create a hash-map/object from the given array and store the array elements as key of object and number of element's occurrence as value of that key in object. 

For understanding hash-map, refer the blog post.

Once done with the object, we will traverse through the object to check which key has highest value and in case of equal values we need to check whose key is higher and accordingly return the result.


  

  

Code solution: 


function highestRank(arr){

  var hash={}

  for(let i=0;i<arr.length;i++){

    if(hash[arr[i]]) hash[arr[i]]++

    else

      hash[arr[i]]=1

  }

  var countMax=0;

  var valueMax=0;

  for(element in hash){

      if(countMax<=hash[element]){

          valueMax=Math.max(element,valueMax)

          countMax=Math.max(hash[element],countMax)

      }

  }

  return valueMax

}

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