The question
Given a word, verify if it is a palindrome excluding spaces and punctuation.
The solution
This is the algorithm I came up to find out if a word is a palindrome:
– Place a pointer(left) on the first character
– Place a pointer(right) on the last character
– Check if the element at left is a character (not punctuation or space)
– If the element is not a character move the pointer one space to the right until you find a character
– Check if the element at right is a character
– If the element is not a character move the pointer one space to the left
– If left is greater than right return true
– Check if left and right elements are the same
– If they are not the same return false
– If they are the same move left one space to the right and right one space to the left
– Start over from step three
This would be the JavaScript implementation:
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var palindrome = 'Anita lava la tina';
var palindrome2 = 'A man, a plan, a canal: Panama';
var notPalindrome = 'A man is not panama';
function isPalindrome(word) {
function isCharacter(needle) {
var haystack = 'ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz';
if (-1 !== haystack.indexOf(needle)) {
return true;
}
return false;
}
var left = 0;
var right = word.length - 1;
while (left <= right) {
while (!isCharacter(word[left])) {
left++;
}
while(!isCharacter(word[right])) {
right--;
}
if (word[left].toLowerCase() !== word[right].toLowerCase()) {
return false;
}
left++;
right--;
}
return true;
}
console.log(isPalindrome(palindrome)); // true
console.log(isPalindrome(palindrome2)); // true
console.log(isPalindrome(notPalindrome)); // false
computer_science algorithms javascript programming