diff --git a/001 Two Sum.py b/001 Two Sum.py
index 88e5548..b931407 100644
--- a/001 Two Sum.py	
+++ b/001 Two Sum.py	
@@ -9,16 +9,12 @@
 Input: numbers={2, 7, 11, 15}, target=9
 Output: index1=1, index2=2
 """
-__author__ = 'Danyang'
 
 
 class Solution:
     def twoSum_TLE(self, num, target):
         """
         built-in method .index
-        :param num: list
-        :param target: int
-        :return: tuple, (index1, index2)
         """
         nums = num
         for ind1, val in enumerate(nums):
@@ -37,10 +33,6 @@ def twoSum_TLE_2(self, num, target):
     def twoSum(self, num, target):
         """
         Hash Map
-
-        :param num: list
-        :param target: int
-        :return: tuple, (index1, index2)
         """
         hash_map = {}
         for ind, val in enumerate(num):
@@ -54,4 +46,4 @@ def twoSum(self, num, target):
 
 
 if __name__=="__main__":
-    print Solution().twoSum([3, 2, 4], 6)
\ No newline at end of file
+    print(Solution().twoSum([3, 2, 4], 6))
\ No newline at end of file
diff --git a/004 Add Two Numbers.py b/002 Add Two Numbers.py
similarity index 92%
rename from 004 Add Two Numbers.py
rename to 002 Add Two Numbers.py
index dcc6364..5ff1d77 100644
--- a/004 Add Two Numbers.py	
+++ b/002 Add Two Numbers.py	
@@ -76,4 +76,5 @@ def addNode(self, node1, node2):
         l1s[i].next = l1s[i+1]
     for i in range(len(l2s)-1):
         l2s[i].next = l2s[i+1]
-    Solution().addTwoNumbers(l1s[0], l2s[0])
+    solution = Solution().addTwoNumbers(l1s[0], l2s[0])
+    print(solution)
diff --git a/003 Longest Substring Without Repeating Characters.py b/003 Longest Substring Without Repeating Characters.py
index c9c5747..df8dd83 100644
--- a/003 Longest Substring Without Repeating Characters.py	
+++ b/003 Longest Substring Without Repeating Characters.py	
@@ -36,4 +36,6 @@ def lengthOfLongestSubstring(self, s):
 
             visited_last_index[ord(val)] = ind  # update last visited index
 
-        return longest
\ No newline at end of file
+        return longest
+
+print(Solution().lengthOfLongestSubstring("abcabcbb"))
\ No newline at end of file
diff --git a/002 Median of Two Sorted Arrays.py b/004 Median of Two Sorted Arrays.py
similarity index 71%
rename from 002 Median of Two Sorted Arrays.py
rename to 004 Median of Two Sorted Arrays.py
index 8aebcfa..efd30bd 100644
--- a/002 Median of Two Sorted Arrays.py	
+++ b/004 Median of Two Sorted Arrays.py	
@@ -1,8 +1,7 @@
 """
-There are two sorted arrays A and B of size m and n respectively. Find the median of the two sorted arrays. The overall
-run time complexity should be O(log (m+n)).
+There are two sorted arrays A and B of size m and n respectively.
+Find the median of the two sorted arrays. The overall run time complexity should be O(log (m+n)).
 """
-__author__ = 'Danyang'
 
 
 class Solution:
@@ -23,10 +22,6 @@ def findMedianSortedArrays(self, A, B):
         
         T(N) = T(3/4 N) + O(1), thus T(N) = O(lg N) where N = |A|+|B|
         O(log (m+n)), thus binary search.
-
-        :param A: list
-        :param B: list
-        :return: float
         """
         m = len(A)
         n = len(B)
@@ -36,13 +31,6 @@ def findMedianSortedArrays(self, A, B):
             return self.find_kth(A, B, (m+n)/2)
 
     def find_kth(self, A, B, k):
-        """
-
-        :param A:
-        :param B:
-        :param k: index starting from 0
-        :return:
-        """
         if not A:  return B[k]
         if not B:  return A[k]
         if k == 0: return min(A[0], B[0])
@@ -59,7 +47,7 @@ def find_kth(self, A, B, k):
 
 
 if __name__ == "__main__":
-    assert Solution().findMedianSortedArrays([1, 2], [1, 2, 3]) == 2
-    assert Solution().findMedianSortedArrays([1, 2], [3]) == 2
-    assert Solution().findMedianSortedArrays([1], [2, 3]) == 2
-    assert Solution().findMedianSortedArrays([1, 2], [1, 2]) == 1.5
+    print(Solution().findMedianSortedArrays([1, 2], [1, 2, 3])) #  == 2)
+    print(Solution().findMedianSortedArrays([1, 2], [3]))   # == 2)
+    print(Solution().findMedianSortedArrays([1], [2, 3]))  # == 2)
+    print(Solution().findMedianSortedArrays([1, 2], [1, 2])) # == 1.5)
diff --git a/014 3Sum.py b/014 3Sum.py
index 3100ae5..096df14 100644
--- a/014 3Sum.py	
+++ b/014 3Sum.py	
@@ -126,4 +126,4 @@ def threeSum(self, num):
 
 
 if __name__ == "__main__":
-    print Solution().threeSum([-1, 0, 1, 2, -1, -4])
\ No newline at end of file
+    print(Solution().threeSum([-1, 0, 1, 2, -1, -4]))
\ No newline at end of file
diff --git a/018 4Sum.py b/018 4Sum.py
index a435d05..ee2ea1d 100644
--- a/018 4Sum.py	
+++ b/018 4Sum.py	
@@ -80,16 +80,16 @@ def fourSum(self, num, target):
             return []
         num.sort()
 
-        for p in xrange(length):
-            for q in xrange(p+1, length):
+        for p in range(length):
+            for q in range(p+1, length):
                 # record the pair sum
                 if num[p]+num[q] not in sum2index:
                     sum2index[num[p]+num[q]] = [(p, q)]
                 else:
                     sum2index[num[p]+num[q]].append((p, q))
 
-        for i in xrange(length):
-            for j in xrange(i+1, length-2):
+        for i in range(length):
+            for j in range(i+1, length-2):
                 sum_remain = target-num[i]-num[j]
                 if sum_remain in sum2index:
                     # construct the result
@@ -97,4 +97,6 @@ def fourSum(self, num, target):
                         if pair[0]>j:  # avoid duplicate
                             result_set.add(( num[i], num[j], num[pair[0]], num[pair[1]] ))
 
-        return [list(i) for i in result_set]  # convert tuple to list
\ No newline at end of file
+        return [list(i) for i in result_set]  # convert tuple to list
+
+print(Solution().fourSum([1, 0, -1, 0, -2, 2], 0))
\ No newline at end of file
diff --git a/121 Best Time to Buy and Sell Stock II.py b/121 Best Time to Buy and Sell Stock II.py
index 63c84bb..c42313d 100644
--- a/121 Best Time to Buy and Sell Stock II.py	
+++ b/121 Best Time to Buy and Sell Stock II.py	
@@ -5,7 +5,6 @@
 one share of the stock multiple times). However, you may not engage in multiple transactions at the same time (ie, you
 must sell the stock before you buy again).
 """
-__author__ = 'Danyang'
 
 
 class Solution:
diff --git a/122 Best Time to Buy and Sell Stock.py b/122 Best Time to Buy and Sell Stock.py
index 7f8fe2f..b3f5ee8 100644
--- a/122 Best Time to Buy and Sell Stock.py	
+++ b/122 Best Time to Buy and Sell Stock.py	
@@ -56,4 +56,4 @@ def maxProfitDelta(self, prices):
 
 
 if __name__ == "__main__":
-    assert Solution().maxProfit([3, 2, 1, 4, 5, 6, 2]) == 5
\ No newline at end of file
+    print(Solution().maxProfit([3, 2, 3, 4, 5, 6, 1])) #a   == 5
\ No newline at end of file
diff --git a/146 LRU Cache.py b/146 LRU Cache.py
index 62ed86e..b786a61 100644
--- a/146 LRU Cache.py	
+++ b/146 LRU Cache.py	
@@ -106,10 +106,10 @@ def set(self, key, value):
         :param value: int
         :return: value
         """
-        if key in self.dic:
+        if key in self.dic:  # 可以替换位置，或者删除，再添加
             self.q.remove(key)
             self.q.insert(0, key)
-        else:
+        else:               # 直接插入，并删除尾部
             if len(self.q)+1 <= self.capacity:
                 self.q.insert(0, key)
             else:
@@ -117,3 +117,19 @@ def set(self, key, value):
                 self.q.insert(0, key)
 
         self.dic[key] = value
+
+
+def test():
+    cache = LRUCache(2)
+    cache.set(1, 1)
+    cache.set(2, 2)
+    print(cache.get(1))
+    cache.set(3, 3)   # evicts key 2
+    print(cache.get(2))  #  returns -1 (not found)
+    cache.set(4, 4)  # evicts key 1
+    print(cache.get(1))  # returns -1 (not found)
+    print(cache.get(3))  # returns 3
+    print(cache.get(4))  # returns 4
+
+
+test()
\ No newline at end of file