Leetcode Easy


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

Example 1:

Input: s = "anagram", t = "nagaram"
Output: true

Example 2:

Input: s = "rat", t = "car"
Output: 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?


class Solution {
    public boolean isAnagram(String s, String t) {
        // We can safely assume the two strings are not anagrams
        if (s.length() != t.length())
            return false;

        HashMap<Character, Integer[]> map = new HashMap<>();

        // Add all of the characters and their frequency in the first string
        for (int i = 0; i < s.length(); i++) {
            char curChar = s.charAt(i);

            if (!map.containsKey(curChar))
                map.put(curChar, new Integer[]{0});


        // Check that all the same letters are in the second string
        for (int i = 0; i < t.length(); i++) {
            char curChar = t.charAt(i);

            if (!map.containsKey(curChar) || map.get(curChar)[0] == 0)
                return false;


        return true;

How it works

We add all of the characters and their frequency to a hash map, using an array for the frequency so that we have a mutable object. Then we check to make sure that all of the characters in the second string match those in the first.