solved combination-sums.

Author: sangbeenmoon

combination-sum/sangbeenmoon.py

@@ -0,0 +1,26 @@
+# TC : O(2^target) 재귀 트리의 분기 수
+# SC : O(target/min(candidates)) 재귀 스택 깊이
+
+class Solution: 
+    def combinationSum(self, candidates: List[int], target: int) -> List[List[int]]:
+        self.answer = []
+        for i in range(len(candidates)):
+            self.go(i, candidates, [candidates[i]], candidates[i], target)
+
+        return self.answer
+
+    def go(self, i:int, candidates: List[int], nums: List[int], sum_: int, target: int):
+        if sum_ == target:
+            self.answer.append(nums.copy())
+
+        for j in range(i, len(candidates)):
+            if candidates[j] + sum_ <= target:
+                nums.append(candidates[j])
+                self.go(j, candidates, nums, sum_ + candidates[j], target)
+                nums.pop()
+
+        
+
+
+            
+

valid-palindrome/sangbeenmoon.py

@@ -0,0 +1,21 @@
+# TC : O(n) 
+# SC : O(n)
+
+class Solution:
+    def isPalindrome(self, s: str) -> bool:
+        refined_s = []
+
+        for ch in s:
+            if 'a' <= ch and ch <= 'z' or ('0' <= ch and ch <= '9'):
+                refined_s.append(ch)
+                continue
+
+            if 'A' <= ch and ch <= 'Z':
+                refined_s.append(ch.lower())
+        
+        for i in range(len(refined_s)):
+            j = len(refined_s) - i - 1
+            if refined_s[i] != refined_s[j]:
+                return False
+            
+        return True