CODEWITHSUNDEEP
javascriptexecution-time
Alice378
Alice378

Reputation: 37

How to minimize the execution time?

I'm checking if the given string is palindrom or not, but the execution time is too long.

My code is below:

function checkPalindrome(inputString) {
  for (let i = 0; i < (inputString.length - 1) / 2; i++) {
    const a = inputString[i];
    const b = inputString.split("").reverse().join("")[i];
    if (a !== b) {
      return false;
    }
    continue;
  }
  return true;
}
const palindrome = checkPalindrome("abba");
console.log(palindrome);

How can I optimize the code in order to reduce it's execution time?

Upvotes: 1

Views: 512

Answers (5)

Anonymous Coder
Anonymous Coder

Reputation: 586

here is a little efficient recursive solution

function checkPalindrome(inputString) {
    const n = inputString.length
    if(n == 0 || n == 1)
        return true;
    else{
        if(inputString[0] != inputString[n-1]){
            return false;
        }
    }
    const t = inputString.slice(1, n-1)
    return checkPalindrome(t)
    }

console.log(checkPalindrome("abbca"))

or either more efficient

    function checkPalindrome(inputString) {
        return (inputString.split("").reverse()).join('') === inputString
    }

console.log(checkPalindrome("abba"))

Upvotes: 0

BadPiggie
BadPiggie

Reputation: 6359

Why you are iterating each letter, When you can reverse it using array methods?

function checkPalindrome(inputString) {
  return inputString === inputString.split("").reverse().join("");
}

let palindrome = checkPalindrome("abba");
console.log(palindrome);

palindrome = checkPalindrome("random");
console.log(palindrome);

palindrome = checkPalindrome("abba isi abba");
console.log(palindrome);

Upvotes: 0

flyingturtles
flyingturtles

Reputation: 903

Even better:

function palindrome(str) {
  var re = /[\W_]/g;
  // convert to lower case and remove spaces
  var lower = str.toLowerCase().replace(re, '');
  // reverse the string
  var reverse = lower.split('').reverse().join(''); 
  // check if reversed and actual string is same
  return reverse === lower;
}

console.log(palindrome("sir"))
console.log(palindrome("madam"))

Upvotes: 0

dolor3sh4ze
dolor3sh4ze

Reputation: 1165

You can check with a simple for loop

function checkPalindrome(inputString) {
    const len = inputString.length;
    for (let i = 0; i < len / 2; i++) {
        if (inputString[i] !== inputString[len - 1 - i])
            return 'not a palindrome';
    }
    return 'palindrome';
}

console.log(checkPalindrome('madam'))

Upvotes: 1

Jamiec
Jamiec

Reputation: 136124

Dont repeat yourself! You're splitting and reversing the string every iteration.

function checkPalindrome(inputString) {
  const reversed = inputString.split("").reverse()
  for (let i = 0; i < (inputString.length - 1) / 2; i++) {
    const a = inputString[i];
    const b = reversed[i]
    if (a !== b) {
      return false;
    }
    continue; /// pointless also - you're already at the end of the loop
  }
  return true;
}


console.log(checkPalindrome("sir"))
console.log(checkPalindrome("madam"))

That's the big one, there are other micro optimizations you can make such as not evaluating the loop control every time, but it will make very little difference unless your input is huge.

Upvotes: 0

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