Given an arbitrary ransom note string and another string containing letters from all the magazines, write a function that will return true if the ransom note can be constructed from the magazines ; otherwise, it will return false.

Each letter in the magazine string can only be used once in your ransom note.

class Solution {
    public boolean canConstruct(String ransomNote, String magazine) {
        if(ransomNote == null || ransomNote.length() == 0)
            return true;

        if(magazine == null || magazine.length() == 0)
            return false;

        int[] count = new int[26];
        for(int i = 0; i < magazine.length(); i++)
            count[magazine.charAt(i) - 'a']++;

        for(int i = 0; i < ransomNote.length(); i++) {
            char c = ransomNote.charAt(i);
            count[c - 'a']--;
            if(count[c - 'a'] < 0)
                return false;
        }

        return true;
    }
}