diff --git a/Python/combinationSum.py b/Python/combinationSum.py
new file mode 100644
index 00000000..4021efac
--- /dev/null
+++ b/Python/combinationSum.py
@@ -0,0 +1,14 @@
+class Solution(object):
+    def combinationSum(self, candidates, target):
+        ret = []
+        self.dfs(candidates, target, [], ret)
+        return ret
+    
+    def dfs(self, nums, target, path, ret):
+        if target < 0:
+            return 
+        if target == 0:
+            ret.append(path)
+            return 
+        for i in range(len(nums)):
+            self.dfs(nums[i:], target-nums[i], path+[nums[i]], ret)
diff --git a/Python/recentCOunter.py b/Python/recentCOunter.py
new file mode 100644
index 00000000..06aabb44
--- /dev/null
+++ b/Python/recentCOunter.py
@@ -0,0 +1,10 @@
+class RecentCounter:
+
+    def __init__(self):
+        self.p = collections.deque()        
+
+    def ping(self, t):
+        self.p.append(t)
+        while self.p[0] < t - 3000:
+            self.p.popleft()
+        return len(self.p)
diff --git a/Python/rotateList.py b/Python/rotateList.py
new file mode 100644
index 00000000..8f1bd277
--- /dev/null
+++ b/Python/rotateList.py
@@ -0,0 +1,43 @@
+class Solution(object):
+    def rotateRight(self, head, k):
+        """
+        :type head: ListNode
+        :type k: int
+        :rtype: ListNode
+        """
+        if not head:
+            return None
+    
+        if head.next == None:
+            return head
+        
+        pointer = head
+        length = 1
+    
+        while pointer.next:
+            pointer = pointer.next
+            length += 1
+    
+        rotateTimes = k%length
+    
+        if k == 0 or rotateTimes == 0:
+            return head
+    
+        fastPointer = head
+        slowPointer = head
+    
+        for a in range (rotateTimes):
+            fastPointer = fastPointer.next
+    
+    
+        while fastPointer.next:
+            slowPointer = slowPointer.next
+            fastPointer = fastPointer.next
+    
+        temp = slowPointer.next
+    
+        slowPointer.next = None
+        fastPointer.next = head
+        head = temp
+    
+        return head