[LeetCode] Valid Anagram

Problem: Given two strings s and t, return true if t is an anagram of s, and false otherwise.

An Anagram is a word or phrase formed by rearranging the letters of a different word or phrase, typically using all the original letters exactly once.

Example:

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

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

Constraints:

• 1 <= s.length, t.length <= 5 * 104
• s and t consist of lowercase English letters.

Approach: It's a simple problem to solve using hashmap. Just have a look at implementation directly.

Implementation in C#:

    public bool IsAnagram(string s, string t)

    {

        int length = s?.Length ?? 0;

        if (length != t.Length)

        {

            return false;

        }

        int[] charMap = new int[26];

        foreach (char ch in s)

        {

            ++charMap[ch - 'a'];

        }

        foreach (char ch in t)

        {

            if (charMap[ch - 'a'] == 0)

            {

                return false;

            }

            --charMap[ch - 'a'];

        }

        foreach (int i in charMap)

        {

            if (i != 0)

            {

                return false;

            }

        }

        return true;

    }

Complexity: O(n)