list of answer of hackerrank problem in javascript

HackerRank.js

// 1. https://www.hackerrank.com/challenges/counting-valleys/problem
// count how many valleys has been passed by hiker

function countingValleys(n, s) {
  let valleys = 0;
  let count = 0;
  s.split('').forEach(x => {
  	if (x === 'U') {
      count += 1 
      // check if count === 0 means it is the time when hiker go to sea level from valleys, valleys += 1
      if (count === 0) {
      	valleys += 1
      }
    } else {
      count -= 1
    }
  })
  
  return valleys
}

// 2. https://www.hackerrank.com/challenges/sock-merchant/problem
// find the amount of scokpairs

function sockMerchant(n, ar) {
    // create color hash
    const colors = {};
    // count total matches (pairs)
    let matches = 0;
    ar.forEach(x => {
      // if color with truthy value exist, increment pairs by 1 and set color to zero to make it falsy
      if (colors[x]) {
      	matches++;
        colors[x] = 0
      }
      // if color value is falsy (0 or have no key inside hash), create or add 1
      else {
      	colors[x] = 1
      }
    })
  
  // result of socks pair
  return matches
}