wrote Time/Space Complexities for each algorithm

Author: wclee2265

best-time-to-buy-and-sell-stock/wclee2265.cpp

@@ -1,4 +1,6 @@
 // https://leetcode.com/problems/best-time-to-buy-and-sell-stock/
+// Time Complexity : O(n)
+// Space Complexity : O(1)
 
 class Solution {
 public:

contains-duplicate/wclee2265.cpp

@@ -1,4 +1,6 @@
 // https://leetcode.com/problems/contains-duplicate/
+// Time Complexity : O(n)
+// Space Complexity : O(n)
 
 class Solution {
 public:

two-sum/wclee2265.cpp

@@ -1,4 +1,6 @@
 // https://leetcode.com/problems/two-sum/
+// Time Complexity : O(nlogn)
+// Space Complexity : O(n)
 
 class Solution {
 public:

valid-anagram/wclee2265.cpp

@@ -1,4 +1,6 @@
 // https://leetcode.com/problems/valid-anagram/
+// Time Complexity : O(n)
+// Space Complexity : O(1)
 
 class Solution {
 public:

valid-palindrome/wclee2265.cpp

@@ -1,4 +1,6 @@
 // https://leetcode.com/problems/valid-palindrome/
+// Time Complexity : O(n)
+// Space Complexity : O(n)
 
 class Solution {
 public: