[Yiseull] WEEK 01 solutions

contains-duplicate/Yiseull.py

@@ -0,0 +1,3 @@
+class Solution:
+    def containsDuplicate(self, nums: List[int]) -> bool:
+        return len(nums) != len(set(nums))

longest-consecutive-sequence/Yiseull.py

@@ -0,0 +1,16 @@
+class Solution:
+    def longestConsecutive(self, nums: List[int]) -> int:
+        answer = 0
+        numsSet = set(nums)
+        for num in numsSet:
+            if num - 1 in numsSet:
+                continue
+
+            size = 1
+            while num + 1 in numsSet:
+                size += 1
+                num += 1
+
+            answer = max(answer, size)
+
+        return answer

top-k-frequent-elements/Yiseull.py

@@ -0,0 +1,30 @@
+from collections import Counter
+
+class Solution:
+    def topKFrequent(self, nums: List[int], k: int) -> List[int]:
+        # return [key for key, counter in Counter(nums).most_common(k)]
+
+        # counter = {}
+        # for num in nums:
+        #     if num in counter:
+        #         counter[num] += 1
+        #         continue
+        #     counter[num] = 1
+        #
+        # return [key for key, counter in sorted(counter.items(), key=lambda x: -x[1])[0:k]]
+
+        counter = {}
+        for num in nums:
+            if num in counter:
+                counter[num] += 1
+                continue
+            counter[num] = 1
+
+        heap = [(-v, k) for k, v in counter.items()]
+        heapify(heap)
+
+        answer = []
+        for _ in range(k):
+            answer.append(heappop(heap)[1])
+
+        return answer

two-sum/Yiseull.py

@@ -0,0 +1,7 @@
+class Solution:
+    def twoSum(self, nums: List[int], target: int) -> List[int]:
+        numMap = {}
+        for i, num in enumerate(nums):
+            if target - num in numMap:
+                return [numMap[target- num], i]
+            numMap[num] = i