LintCode 比较字符串题目分析代码

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
        char[] A1 = A.toCharArray();
        char[] B1 = B.toCharArray();
        
        if(B1.length > A1.length)
            return false;
            
        int[] letters = new int[26];
        
        for(int i=0;i<A1.length;i++) {
            letters[A1[i]-'A']++;
        }
        
        for(int i=0;i<B1.length;i++)
        {
            if(letters[B1[i]-'A']<=0)
                return false;
            else
                letters[B1[i]-'A']--;
        }
        return true;
    }
}