week 3 sol

Author: hestia-park

combination-sum/hestia-park.py

@@ -0,0 +1,18 @@
+class Solution:
+    def combinationSum(self, candidates: List[int], target: int) -> List[List[int]]:
+        result = []
+        def dfs(result,remain, path, start):
+            if remain==0:
+                result.append(path[:])
+                return 
+            if remain < 0:
+                return 
+            for i in range(start, len(candidates)):
+                path.append(candidates[i])
+                dfs(result,remain - candidates[i], path, i)  
+                path.pop()  
+
+        dfs(result,target, [], 0)
+        return result
+
+

maximum-subarray/hestia-park.py

@@ -0,0 +1,12 @@
+class Solution:
+    def maxSubArray(self, nums: List[int]) -> int:
+        dp = 0
+        max_ = float('-inf')
+        for i in range(len(nums)):
+            dp += nums[i]
+            max_ = max(max_, dp)
+            if dp < 0:
+                dp = 0  # 누적합이 0보다 작아지면 버리고 새로 시작
+        return max_
+
+

number-of-1-bits/hestia-park.py

@@ -0,0 +1,20 @@
+class Solution:
+    def hammingWeight(self, n: int) -> int:
+        # ans=0
+        # # bit=[]
+        # moc=n
+        # while moc > 0:
+        #     nam=moc%2
+        #     if nam==1:
+        #         ans+=1
+        #     moc=int((moc-nam)/2)
+
+        # return ans
+        # using Brian Kernighan’s Algorithm
+        count = 0
+        while n:
+            n &= n - 1
+            count += 1
+        return count
+
+

valid-palindrome/hestia-park.py

@@ -0,0 +1,20 @@
+class Solution:
+    def isPalindrome(self, s: str) -> bool:
+        # lower_text = s.lower()
+        # clean_text = re.sub(r'[^a-z0-9]', '', lower_text)
+        # if len(clean_text) ==0:
+        #     return True
+        
+        # j = len(clean_text) - 1
+        # ans = True
+
+        # for i in range(len(clean_text) // 2):
+        #     if clean_text[i] != clean_text[j]:
+        #         ans = False
+        #         break
+        #     j -= 1
+        # return ans
+        n = "".join(c for c in s if c.isalnum()).lower()
+        return n == n[::-1]            
+
+