add rivkode 1-3 questions

Author: rivkode

contains-duplicate/rivkode.py

@@ -5,11 +5,14 @@
 # The size of the set for storing deduplicated elements is proportional to the length of the input list.
 
 class Solution:
-    def containsDuplicate(self, nums: list[int]) -> bool:
-        list_len = len(nums)
-        set_len = len(set(nums))
+    def containsDuplicate(self, nums):
+        list_num = len(nums)
+        set_num = len(set(nums))
 
-        return list_len != set_len
+        if list_num != set_num:
+            return True
+        else:
+            return False
 
 if __name__ == "__main__":
     solution = Solution()

top-k-frequent-elements/rivkode.py

@@ -8,18 +8,35 @@
 # - and when sorting takes O(n), hash[x] occupy O(1)
 
 class Solution:
-    def topKFrequent(self, nums: List[int], k: int) -> List[int]:
-        hash = dict()
+    def topKFrequent(self, nums, k):
+        """
+        :type nums: List[int]
+        :type k: int
+        :rtype: List[int]
+        """
 
-        # for loop nums to set count for each element in hash(dictionary)
-        for num in nums:
-            if num in hash:
-                hash[num] += 1
+        dic = {}
+
+        for v in nums:
+            if v in dic:
+                cur = dic[v]
+                cur += 1
+                dic[v] = cur
             else:
-                hash[num] = 1
+                dic[v] = 1
+
+        reverse_desc = sorted(dic.items(), key=lambda item: item[1], reverse=True)
 
-        # sort (TimSort), using lambda function to set a sorting key which is a count
-        return sorted(hash, key=lambda x: hash[x], reverse=True)[:k]
+        n = 0
+        result = []
+        for v in reverse_desc:
+            if n == k:
+                break
+            
+            result.append(v[0])
+            n += 1
+        
+        return result
 
 if __name__ == "__main__":
     solution = Solution()

two-sum/rivkode.py

@@ -0,0 +1,18 @@
+class Solution(object):
+    def twoSum(self, nums, target):
+
+        """
+        :type nums: List[int]
+        :type target: int
+        :rtype: List[int]
+        """
+
+        dic = {}
+        
+        for i, v in enumerate(nums):
+            complement = target - v
+
+            if complement in dic:
+                return [i, dic[complement]]
+            
+            dic[v] = i