PalindromePermutationCheck.java

package Leetcode;

import java.util.HashSet;
import java.util.Set;

/**
 * @author kalpak
 *
 * Given a string, determine if a permutation of the string could form a palindrome.
 *
 * Example 1:
 *
 * Input: "code"
 * Output: false
 *
 * Example 2:
 *
 * Input: "aab"
 * Output: true
 *
 * Example 3:
 *
 * Input: "carerac"
 * Output: true
 */

public class PalindromePermutationCheck {
    public static boolean canPermutePalindrome(String s) {
        Set<Character> uniqueCharacter = new HashSet<>();

        for(int i = 0; i < s.length(); i++) {
            if(uniqueCharacter.contains(s.charAt(i)))
                uniqueCharacter.remove(s.charAt(i));
            else {
                uniqueCharacter.add(s.charAt(i));
            }
        }
        return uniqueCharacter.size() <= 1;
    }

    public static void main(String[] args) {
        System.out.println(canPermutePalindrome("madam"));
        System.out.println(canPermutePalindrome("abcd"));
    }
}