lintcode-easy-Compare Strings

public class Solution {
    /**
     * @param A : A string includes Upper Case letters
     * @param B : A string includes Upper Case letter
     * @return :  if string A contains all of the characters in B return true else return false
     */
    public boolean compareStrings(String A, String B) {
        // write your code here
        if(A == null)
            return false;
        
        if(B == null || B.length() == 0)
            return true;
        
        int[] count = new int[26];
        
        int lengthA = A.length();
        int lengthB = B.length();
        
        if(lengthB > lengthA)
            return false;
        
        for(int i = 0; i < lengthA; i++){
            count[A.charAt(i) - ‘A‘]++;
        }
        
        for(int i = 0; i < lengthB; i++){
            count[B.charAt(i) - ‘A‘]--;
            
            if(count[B.charAt(i) - ‘A‘] < 0)
                return false;
        }
        
        return true;
    }
}