diff --git a/contains-duplicate/printjin-gmailcom.py b/contains-duplicate/printjin-gmailcom.py
new file mode 100644
index 000000000..c9851976c
--- /dev/null
+++ b/contains-duplicate/printjin-gmailcom.py
@@ -0,0 +1,3 @@
+class Solution:
+    def containsDuplicate(self, nums): 
+        return len(nums) != len(set(nums))
diff --git a/house-robber/printjin-gmailcom.py b/house-robber/printjin-gmailcom.py
new file mode 100644
index 000000000..de03a9232
--- /dev/null
+++ b/house-robber/printjin-gmailcom.py
@@ -0,0 +1,9 @@
+class Solution:
+    def rob(self, nums):
+        num_map = {}
+        for i, num in enumerate(nums):
+            left = num_map.get(i - 2, 0)
+            leftleft = num_map.get(i - 3, 0)
+            num_map[i] = max(left + num, leftleft + num)  
+        return max(num_map.get(len(nums) - 1, 0), num_map.get(len(nums) - 2, 0))
+
diff --git a/longest-consecutive-sequence/printjin-gmailcom.py b/longest-consecutive-sequence/printjin-gmailcom.py
new file mode 100644
index 000000000..7b7188efd
--- /dev/null
+++ b/longest-consecutive-sequence/printjin-gmailcom.py
@@ -0,0 +1,13 @@
+class Solution:
+    def longestConsecutive(self, nums):
+        num_set = set(nums)
+        longest = 0
+        for num in num_set:
+            if num - 1 not in num_set:
+                current = num
+                length = 1
+                while current + 1 in num_set:
+                    current += 1
+                    length += 1
+                longest = max(longest, length)
+        return longest
diff --git a/top-k-frequent-elements/printjin-gmailcom.py b/top-k-frequent-elements/printjin-gmailcom.py
new file mode 100644
index 000000000..9e30def0d
--- /dev/null
+++ b/top-k-frequent-elements/printjin-gmailcom.py
@@ -0,0 +1,6 @@
+from collections import Counter
+
+class Solution:
+    def topKFrequent(self, nums, k):
+        count = Counter(nums)
+        return [num for num, _ in count.most_common(k)]
diff --git a/two-sum/printjin-gmailcom.py b/two-sum/printjin-gmailcom.py
new file mode 100644
index 000000000..437d04e4b
--- /dev/null
+++ b/two-sum/printjin-gmailcom.py
@@ -0,0 +1,9 @@
+class Solution:
+    def twoSum(self, nums, target):
+        num_map = {}
+        for i, num in enumerate(nums):
+            left = target - num
+            if left in num_map:
+                return [num_map[left], i]
+            num_map[num] = i  
+