Problem solving approach

//sum 2 numbers and return the result
//addition of two numbers
//input - 10, 15 //output - 25
//input 20, 30  //output 50
//input 20.33, 40.5345 //output - 60

// function sum(num1, num2) {
//   //output
//   return num1 + num2
// }
// sum(10, 20)

//count the character
//input - string 'Hello' output- {h: 1, e: 1, l: 2, o: 1}
//input - string 'greet' output- {g: 1, r: 1, e: 2, t: 1}

//time complexity O(n)
//space complexity O(n)
// function countCharacter(str) {
//creating an object for tracking the frequency of element
//   const hashMap = {}

// looping the input anf generalize the case
//   const normalizeStr = str.toLowerCase()
//   for (let i = 0; i < normalizeStr.length; i++) {
// if there is any space ignore it
// const char = normalizeStr[i]
// if (char === ' ') continue
//ternary
// char in hashMap ?  hashMap[char] = hashMap[char] + 1 : hashMap[char] = 1
// hashMap[char] = (hashMap[char] || 0) + 1
// if (char in hashMap) {
//   //check if the element exists on the object increment the existent count value
//   hashMap[char] = hashMap[char] + 1
// } else {
//   // if element not present assign the value 1
//   hashMap[char] = 1
// }
//   }
//   return hashMap
// }
// console.log(countCharacter('He llo'))

//check the element of first array 2nd array
//if the element exists
//return true
//otherwise false

// input- arr1-['a', 'b', 'c'] arr2-[1, 2, 3, 'z'] //false
// input- arr1-['a', 'b', 'c'] arr2-[1, 2, 3, 'c'] //true
//time complexity O(n * m)
//space complexity O(1)
// function isElementExists(arr1, arr2) {
//     //flag variable
//     let exists = false
//     for(let elm of arr1){
//        if(arr2.includes(elm)){
//         exists = true
//         break
//        }
//     }

//     return exists
//   }

// time complexity O(n + m)
//space complexity O(n)
function isElementExists(arr1, arr2) {
  const frequencyCounter = {}
  for (let elm of arr1) {
    frequencyCounter[elm] = true
  }

  for (let elm of arr2) {
    if (elm in frequencyCounter) {
      return true
    }
  }
}

console.log(isElementExists(['a', 'b', 'c'], [1, 2, 3, 'b']))