feat: 2주차 문제풀이

Author: 최준영[chris][Tech]

3sum/chrisjune.py

@@ -0,0 +1,17 @@
+from typing import List
+
+
+class Solution:
+    def threeSum(self, nums: List[int]) -> List[List[int]]:
+        if len(nums) >= 3 and set(nums) == set([0]):
+            return [[0, 0, 0]]
+        triplets = set()
+        for i in range(len(nums) - 2):
+            seen = set()
+            for j in range(i + 1, len(nums)):
+                f = -(nums[i] + nums[j])
+                if f in seen:
+                    triplet = [nums[i], nums[j], f]
+                    triplets.add(tuple(sorted(triplet)))
+                seen.add(nums[j])
+        return list(triplets)

climbing-stairs/chrisjune.py

@@ -0,0 +1,10 @@
+class Solution:
+    def climbStairs(self, n: int) -> int:
+        if n <= 1:
+            return 1
+        dp = [0] * n
+        dp[0] = 1
+        dp[1] = 2
+        for i in range(3,n+1):
+            dp[i-1] = dp[i-2] + dp[i-3]
+        return dp[n-1]

product-of-array-except-self/chrisjune.py

@@ -0,0 +1,19 @@
+from typing import List
+
+
+class Solution:
+    def productExceptSelf(self, nums: List[int]) -> List[int]:
+        len_n = len(nums)
+        front_cum = [1] * len_n
+        back_cum = [1] * len_n
+
+        for i in range(1, len_n):
+            front_cum[i] = front_cum[i - 1] * nums[i - 1]
+
+        for j in range(1, len_n):
+            idx = len_n - j - 1
+            back_cum[idx] = back_cum[idx + 1] * nums[idx + 1]
+
+        final = [front_cum[i] * back_cum[i] for i in range(len_n)]
+
+        return final

valid-anagram/chrisjune.py

@@ -0,0 +1,3 @@
+class Solution:
+    def isAnagram(self, s: str, t: str) -> bool:
+        return sorted(s) == sorted(t)