Valid Anagram

给两个字符串s和t, 看看是不是互为重组.

public class Solution {
    public boolean isAnagram(String s, String t) {
        int[] s_count = new int[256];
        int[] t_count = new int[256];
        for(int i = 0 ; i < s.length(); i++)
            s_count[s.charAt(i)]++;
        for(int i = 0 ; i < t.length(); i++)
            t_count[t.charAt(i)]++;
        return hash(s_count) == hash(t_count);
    }
    
    public int hash(int[] count){
        int a = 3;
        int b = 7;
        int hash = 0;
        
        for(int i = 0 ; i < count.length; i++){
            hash += count[i]*a + b;
            a*=b;
        }
        return hash;
    }
}