add 4, 5 questions

Author: rivkode

house-robber/rivkode.py

@@ -0,0 +1,18 @@
+class Solution(object):
+    def rob(self, nums):
+        """
+        :type nums: List[int]
+        :rtype: int
+        """
+        memo = {}
+
+        def dfs(start):
+            if start in memo:
+                return memo[start]
+            if not start < len(nums):
+                memo[start] = 0
+            else:
+                memo[start] = max(nums[start] + dfs(start + 2), dfs(start + 1))
+            return memo[start]
+
+        return dfs(0)

longest-consecutive-sequence/rivkode.py

@@ -0,0 +1,19 @@
+class Solution(object):
+    def longestConsecutive(self, nums):
+        """
+        :type nums: List[int]
+        :rtype: int
+        """
+        num_set = set(nums)
+        longest = 0
+
+        for num in nums:
+            if num - 1 in num_set:
+                continue
+            
+            length = 1
+            while num + length in num_set:
+                length += 1
+            longest = max(length, longest)
+        return longest
+        

two-sum/rivkode.py

@@ -15,4 +15,4 @@ def twoSum(self, nums, target):
             if complement in dic:
                 return [i, dic[complement]]
 
-            dic[v] = i
+            dic[v] = i