Example Problem- Problem Solving Approach

// function countCharacter(inputStr) {
//   convert the string to lowercase
//   const lowerCaseStr = inputStr.toLowerCase()
//   Remove Spaces and special characters
//   const cleanStr = lowerCaseStr.replace(/[^a-z0-9]/gi, '')
//   create a object to hold the counts or frequency
//   const charCount = {}
//    loop the cleaned string and count each character
//   for (let i = 0; i < cleanStr.length; i++) {
//     const char = cleanStr[i]
//     if (charCount[char]) {
//       charCount[char] += 1
//     } else {
//       charCount[char] = 1
//     }
//   }

//  return the result
//   return charCount
// }
// countCharacter('Hel @lo') // Output: { h: 1, e: 1, l: 2, o: 1 }

//optimization
//Time complexity - O(n + n) = O(n)
//Space complexity- O(n)

// function countCharacter(inputStr) {
//   convert the string to lowercase
//   const lowerCaseStr = inputStr.toLowerCase()
//   create a object to hold the counts or frequency
//   const charCount = {}
//   loop the cleaned string and count each character
//   for (let i = 0; i < lowerCaseStr.length; i++) {
//     const char = lowerCaseStr[i]
//    Remove Spaces and special characters during add frequency of the character to object
//     if ((char >= 'a' && char <= 'z') || (char >= '0' && char <= '9')) {
//ternary operator
// charCount[char] = charCount[char] ? charCount[char] + 1 : 1
//Alternate solution
//       charCount[char] = (charCount[char] || 0) + 1
//     }
//   }

// return the result
//   return charCount
// }
// console.log(countCharacter('Hel @lo'))
// console.log(countCharacter('')) // Output: {}
// console.log(countCharacter('Hello123!@#Hello'))
// console.log(countCharacter('héllo😊héllo'))

//time complexity O(n * m) -> O(nm)
//space complexity - O(1)
// function isElementExists(arr1, arr2) {
// loop arr1 and check each element with 2nd array element
//   for (let elm of arr1) {
//compare each element with 2nd arr element
// if (arr2.includes(elm)) {
//   return true
// }
//     for (let elm2 of arr2) {
//       if (elm === elm2) {
//         return true
//       }
//     }
//   }

//   return false
// }
//Time Complexity O(m +  n)
//Space complexity - O(n)
function isElementExists(arr1, arr2) {
  //loop arr1 and tack down each data
  //   const trackingObj = {}

  //   for (let elm of arr1) {
  //     trackingObj[elm] = true
  //   }

  const arr1Set = new Set(arr1)
  console.log(arr1Set)
  //loop arr2 and check each element existence in the tracking Object
  for (let elm of arr2) {
    // if (elm in trackingObj) {
    //   return true
    // }
    if (arr1Set.has(elm)) {
      return true
    }
  }
  return false
}
console.log(isElementExists(['a', 'b', 'z'], [1, 2, 3, 'z']))
console.log(isElementExists(['a'], [])) // Output: false
console.log(isElementExists([], [1, 2, 3])) // Output: false
console.log(isElementExists(['x', 'y', 'z'], [1, 2, 3, 'a'])) // Output: false
console.log(isElementExists(['a', 'b', 'c'], [1, 2, 3, 'b'])) // Output: true
console.log(isElementExists(['a', 'b', 'c'], ['a', 'b', 'c'])) // Output: true
console.log(isElementExists(['a', 'b', 'c'], ['a', 'b', 'c'])) // Output: true
console.log(isElementExists(['1', '2', '3'], [1, 2, 3])) // Output: false
console.log(isElementExists([1, 2, 3], [1, 2, 3, '1'])) // Output: true