[LeetCode 242] Valid Anagram

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.

solution:

compare char count between two string

public boolean isAnagram(String s, String t) {
        if(s.length()!=t.length()) return false;
        Map<Character, Integer> count = new HashMap<>();
        for(int i=0;i<s.length();i++){
            char c = s.charAt(i);
            if(!count.containsKey(c)){
                count.put(c, 1);
            }else{
                int num = count.get(c);
                count.put(c, num+1);
            }
        }
        for(int i=0;i<t.length();i++){
            char c = t.charAt(i);
            if(!count.containsKey(c)){
                return false;
            }else{
                int num = count.get(c);
                count.put(c, num-1);
            }
        }
        for(char key:count.keySet()){
            if(count.get(key)!=0)
                return false;
        }
        return true;
    }