number 5 solved

Author: devyulbae

contains-duplicate/devyulbae.py

@@ -15,4 +15,5 @@ def containsDuplicate(self, nums: List[int]) -> bool:
             if count > 1:
                 return True
 
-        return False
+        return False
+    

house-robber/devyulbae.py

@@ -16,11 +16,24 @@ def rob(self, nums: List[int]) -> int:
         if not nums:
             return 0
 
-        def dfs(s):
+        memo = {}
+
+        def dfs(s, memo):
             if s >= len(nums):
                 return 0
-            return max(dfs(s+1), nums[s] + dfs(s+2))
+            if s+1 in memo:
+                prev1 = memo[s+1]
+            else:
+                prev1 = dfs(s+1, memo)
+                memo[s+1] = prev1
+            
+            if s+2 in memo:
+                prev2 = memo[s+2]
+            else:
+                prev2 = dfs(s+2, memo)
+                memo[s+2] = prev2
+
+            return max(prev1, prev2 + nums[s])
 
-        return dfs(0)
+        return dfs(0, memo)
 
-        

top-k-frequent-elements/devyulbae.py

@@ -12,4 +12,5 @@ def topKFrequent(self, nums: List[int], k: int) -> List[int]:
         num_counter = Counter(nums) 
         # {1:1, 2:3, 3:1} -> [(2,3), (1,1), (3,1)]
         sorted_items = sorted(num_counter.items(), key=lambda x: x[1], reverse=True)
-        return [item[0] for item in sorted_items[:k]]
+        return [item[0] for item in sorted_items[:k]]
+    

two-sum/devyulbae.py

@@ -8,4 +8,5 @@ def twoSum(self, nums: List[int], target: int) -> List[int]:
         for i in range(len(nums)):
             for j in range(i+1, len(nums)):
                 if nums[i] + nums[j] == target:
-                    return [i, j]
+                    return [i, j]
+