hasPalindromePermutation.js

// Write an efficient function that checks whether any permutation ↴ of an input string is a palindrome. ↴

// You can assume the input string only contains lowercase letters.

// Examples:

// "civic" should return true
// "ivicc" should return true
// "civil" should return false
// "livci" should return false

function hasPalindromePermutation(theString) {
  let set = new Set();
  for (let i = 0; i < theString.length; i++) {
    if (set.has(theString[i])) {
      set.delete(theString[i]);
    } else {
      set.add(theString[i]);
    }
  }
  return set.size <= 1;
}


















// Tests

let desc = 'permutation with odd number of chars';
assertEqual(hasPalindromePermutation('aabcbcd'), true, desc);

desc = 'permutation with even number of chars';
assertEqual(hasPalindromePermutation('aabccbdd'), true, desc);

desc = 'no permutation with odd number of chars';
assertEqual(hasPalindromePermutation('aabcd'), false, desc);

desc = 'no permutation with even number of chars';
assertEqual(hasPalindromePermutation('aabbcd'), false, desc);

desc = 'empty string';
assertEqual(hasPalindromePermutation(''), true, desc);

desc = 'one character string ';
assertEqual(hasPalindromePermutation('a'), true, desc);

function assertEqual(a, b, desc) {
  if (a === b) {
    console.log(`${desc} ... PASS`);
  } else {
    console.log(`${desc} ... FAIL: ${a} != ${b}`);
  }
}