feat: Implement solution for 242. Valid Anagram and update README

Solved-Problems/Valid_Anagram/Main.java

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+import java.util.HashMap;
+import java.util.Map;
+
+class Main {
+  public boolean isAnagram(String s, String t) {
+    if (s.length() != t.length()) {
+      return false;
+    }
+
+    Map<Character, Integer> countS = new HashMap<>();
+    Map<Character, Integer> countT = new HashMap<>();
+
+    for (int i = 0; i < s.length(); i++) {
+      char c1 = s.charAt(i);
+      countS.put(c1, countS.getOrDefault(c1, 0) + 1);
+    }
+
+    for (int i = 0; i < t.length(); i++) {
+      char c2 = t.charAt(i);
+      countT.put(c2, countT.getOrDefault(c2, 0) + 1);
+    }
+
+    for (char c : countS.keySet()) {
+      if (!countT.containsKey(c) || !countT.get(c).equals(countS.get(c))) {
+        return false;
+      }
+    }
+
+    return true;
+  }
+}

Solved-Problems/Valid_Anagram/Readme.md

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+# Valid Anagram
+Problem Name: 242. Valid Anagram
+
+Approach: Using Hash Maps
+
+Difficulty: Easy
+
+Link: [Leetcode](https://leetcode.com/problems/valid-anagram/description/)
+
+Explanation:
+
+In this problem, we are given two strings, s and t. We need to determine if t is an anagram of s. An anagram is a word or phrase formed by rearranging the letters of another word or phrase, typically using all the original letters exactly once.
+
+Solution Explanation
+
+Check Lengths:
+First, check if the lengths of the two strings are equal. If not, return false immediately as they cannot be anagrams.
+Count Characters:
+
+Use two hash maps to count the frequency of each character in the strings s and t.
+Iterate through the characters of s and update the count in countS.
+Similarly, iterate through the characters of t and update the count in countT.
+Compare Counts:
+
+Compare the two hash maps. If both maps are identical, then t is an anagram of s.
+
+Examples
+
+Example 1:
+Input: s = "anagram", t = "nagaram"
+Output: true
+
+Example 2:
+Input: s = "rat", t = "car"
+Output: false
+
+Constraints
+1 <= s.length, t.length <= 5 * 10^4
+s and t consist of lowercase English letters.