feat: solve valid anagram

Author: GangBean

valid-anagram/GangBean.java

@@ -0,0 +1,31 @@
+class Solution {
+    public boolean isAnagram(String s, String t) {
+        /**
+            1. 문제 이해.
+            - 아나그램: 문자의 순서만 바뀌었을 때 동일한 글자
+            - 구성 문자와 숫자만 동일하면 아나그램
+            2. 풀이 방식
+            - comapre s.length() with t.length()
+            - loop over s and t, count each word's character and it's count, and then save it as map(key-value pair structure)
+            - compare map of s and t
+            3. Complexity
+            - time complexity: O(N)
+            - space complexity: O(N)
+        */
+
+        if (s.length() != s.length()) return false;
+
+        Map<Character, Integer> sMap = new HashMap<>();
+        Map<Character, Integer> tMap = new HashMap<>();
+
+        for (char c: s.toCharArray()) {
+            sMap.put(c, sMap.getOrDefault(c, 0) + 1);
+        }
+        for (char c: t.toCharArray()) {
+            tMap.put(c, tMap.getOrDefault(c, 0) + 1);
+        }
+
+        return Objects.equals(sMap, tMap);
+    }
+}
+