[chrisjune] week 01 solutions

contains-duplicate/chrisjune.py

@@ -0,0 +1,9 @@
+class Solution:
+    def containsDuplicate(self, nums) -> bool:
+        dic = {}
+        for num in nums:
+            dic[num] = dic.get(num, 0) + 1
+        for v in dic.values():
+            if v > 1:
+                return True
+        return False

house-robber/chrisjune.py

@@ -0,0 +1,12 @@
+from typing import List
+
+
+class Solution:
+    def rob(self, nums: List[int]) -> int:
+        if len(nums) <= 1:
+            return nums[0]
+        dp = [0] * len(nums)
+        dp[0], dp[1] = nums[0], max(nums[0], nums[1])
+        for i in range(2, len(nums)):
+            dp[i] = max(dp[i - 1], nums[i] + dp[i - 2])
+        return dp[-1]

longest-consecutive-sequence/chrisjune.py

@@ -0,0 +1,18 @@
+from typing import List
+
+
+class Solution:
+    def longestConsecutive(self, nums: List[int]) -> int:
+        if len(nums) < 1:
+            return 0
+        nums = list(set(nums))
+        nums.sort()
+        dp = [0] * len(nums)
+        dp[0] = 1
+        for i in range(1, len(nums)):
+            if nums[i - 1] + 1 == nums[i]:
+                dp[i] = dp[i - 1] + 1
+            else:
+                dp[i] = 1
+        print(dp)
+        return max(dp)

top-k-frequent-elements/chrisjune.py

@@ -0,0 +1,12 @@
+from typing import List
+
+
+class Solution:
+    def topKFrequent(self, nums: List[int], k: int) -> List[int]:
+        dic = {}
+        for num in nums:
+            dic[num] = dic.get(num, 0) + 1
+        l = [(k, v) for k, v in dic.items()]
+        l.sort(reverse=True, key=lambda x: x[1])
+        l = [i for i, _ in l]
+        return l[:k]

two-sum/chrisjune.py

@@ -0,0 +1,11 @@
+from typing import List
+
+
+class Solution:
+    def twoSum(self, nums: List[int], target: int) -> List[int]:
+        nums_dic = {num: idx for idx, num in enumerate(nums)}
+        for i in range(len(nums)):
+            remain = target - nums[i]
+            exists_idx = nums_dic.get(remain)
+            if exists_idx and exists_idx != i:
+                return i, exists_idx