Week 1 - 3/5

Author: liza0525

contains-duplicate/liza0525.py

@@ -0,0 +1,8 @@
+class Solution:
+    def containsDuplicate(self, nums: List[int]) -> bool:
+        check_set = set()
+        for num in nums:
+            if num in check_set:
+                return True
+            check_set.add(num)
+        return False

top-k-frequent-elements/liza0525.py

@@ -0,0 +1,10 @@
+class Solution:
+    def topKFrequent(self, nums: List[int], k: int) -> List[int]:
+        from collections import defaultdict
+        num_dict = defaultdict(int)
+
+        for num in nums:
+            num_dict[num] += 1
+
+        results = list(map(lambda x: x[0], sorted(num_dict.items(), key=lambda x: -x[1])))
+        return results[:k]

two-sum/liza0525.py

@@ -0,0 +1,11 @@
+class Solution:
+    def twoSum(self, nums: List[int], target: int) -> List[int]:
+        idx_map = {
+            num: idx
+            for idx, num in enumerate(nums)
+        }
+
+        for idx, num in enumerate(nums):
+            result_num = target - num 
+            if result_num in idx_map and idx != idx_map[result_num]:
+                return [idx, idx_map[result_num]]