Anagram of string by counting frequency of each chars and using sorting string

Author: Antesh Sharma

src/main/java/com/antesh/dsa/string/Anagram.java

@@ -0,0 +1,90 @@
+package com.antesh.dsa.string;
+
+
+import java.util.*;
+
+public class Anagram {
+
+    //If using HashMap for frequency count of each character
+    static boolean isAnagram(String a, String b) {
+
+        if ((a == null && b != null) || (a != null && b == null)) {
+            return false;
+        }
+
+        if (a.length() != b.length()) {
+            return false;
+        }
+
+        a = a.toLowerCase();
+        b = b.toLowerCase();
+
+        Map<Character, Integer> freq1 = new HashMap<>();
+        for (int i = 0; i < a.length(); i++) {
+            if (freq1.containsKey(a.charAt(i))) {
+                freq1.put(a.charAt(i), freq1.get(a.charAt(i)) + 1);
+            } else {
+                freq1.put(a.charAt(i), 1);
+            }
+        }
+
+        Map<Character, Integer> freq2 = new HashMap<>();
+        for (int i = 0; i < b.length(); i++) {
+            if (freq2.containsKey(b.charAt(i))) {
+                freq2.put(b.charAt(i), freq2.get(b.charAt(i)) + 1);
+            } else {
+                freq2.put(b.charAt(i), 1);
+            }
+        }
+
+        return freq1.equals(freq2);
+    }
+
+    static boolean isAnagramUsingSort(String a, String b) {
+        if ((a == null && b != null) || (a != null && b == null)) {
+            return false;
+        }
+
+        if (a.length() != b.length()) {
+            return false;
+        }
+
+        a = a.toLowerCase();
+        b = b.toLowerCase();
+
+        char[] charsA = a.toCharArray();
+        charsA = sort(charsA);
+        a = new String(charsA);
+
+        char[] charsB = b.toCharArray();
+        charsB = sort(charsB);
+        b = new String(charsB);
+
+        return a.equals(b);
+
+    }
+
+    //Optimization needed scope: sort in O(log(n))
+    static char[] sort(char[] chars) {
+        for (int i = 0; i < chars.length; i++) {
+            for (int j = i + 1; j < chars.length; j++) {
+                if (chars[j] < chars[i]) {
+                    char temp = chars[i];
+                    chars[i] = chars[j];
+                    chars[j] = temp;
+                }
+            }
+        }
+
+        return chars;
+    }
+
+
+    public static void main(String[] args) {
+        boolean ret = isAnagram("anagram", "margana");
+        System.out.println((ret) ? "Anagrams" : "Not Anagrams");
+
+        ret = isAnagramUsingSort("anagram", "margana");
+        System.out.println((ret) ? "Anagrams" : "Not Anagrams");
+    }
+}