242. Valid Anagram

Description

Given two strings s and t, write a function to determine if t is an anagram of s.

For example,
s = "anagram", t = "nagaram", return true.
s = "rat", t = "car", return false.

Note:
You may assume the string contains only lowercase alphabets.

Follow up:
What if the inputs contain unicode characters? How would you adapt your solution to such case?

Solution

HashTable

class Solution {
    public boolean isAnagram(String s, String t) {
        if (s == null || t == null || s.length() != t.length()) {
            return false;
        }
        
        int[] count = new int[26];
        for (int i = 0; i < s.length(); ++i) {
            ++count[s.charAt(i) - 'a'];
        }
        
        for (int i = 0; i < t.length(); ++i) {
            int j = t.charAt(i) - 'a';
            --count[j];
            if (count[j] < 0) {
                return false;
            }
        }
        
        return true;
    }
}