adds time/space data

Author: anishLearnsToCode

src/ContainsDuplicate.java

@@ -1,3 +1,7 @@
+// https://leetcode.com/problems/contains-duplicate
+// T: O(N)
+// S: O(N)
+
 import java.util.HashSet;
 import java.util.Set;
 

src/TwoSum.java

@@ -1,4 +1,6 @@
 // https://leetcode.com/problems/two-sum/
+// T: O(N)
+// S: O(N)
 
 import java.util.Arrays;
 import java.util.HashMap;