adds time and space complexity for #242

Author: anishLearnsToCode

src/ValidAnagram.java

@@ -1,3 +1,8 @@
+// https://leetcode.com/problems/valid-anagram
+// T: O(|s| + |t|)
+// S: O(1)
+
+
 import java.util.HashMap;
 import java.util.Map;