[daiyongg-kim] WEEK 03 solutions

combination-sum/daiyongg-kim.py

@@ -0,0 +1,26 @@
+class Solution:
+    def combinationSum(self, candidates: List[int], target: int) -> List[List[int]]:
+        candidates.sort()
+        result = []
+
+        def backtracking(start_index, current_combination, current_sum):
+            if current_sum == target:
+                result.append(list(current_combination))
+                return
+
+            if current_sum > target:
+                return
+
+            for i in range(start_index, len(candidates)):
+                candidate = candidates[i]
+
+                if current_sum + candidate > target:
+                    break
+
+                current_combination.append(candidate)
+                backtracking(i, current_combination, current_sum + candidate)
+
+                current_combination.pop()
+
+        backtracking(0, [], 0)
+        return result

maximum-subarray/daiyongg-kim.py

@@ -0,0 +1,10 @@
+class Solution:
+    def maxSubArray(self, nums: List[int]) -> int:
+        current_sum = nums[0]
+        max_sum = nums[0]
+
+        for i in range(1, len(nums)):
+            current_sum = max(nums[i], current_sum + nums[i])
+            max_sum = max(current_sum, max_sum)
+
+        return max_sum

number-of-1-bits/daiyongg-kim.py

@@ -0,0 +1,10 @@
+class Solution:
+    def hammingWeight(self, n: int) -> int:
+        cnt = 0
+
+        while n != 0:
+            if n & 1:
+                cnt += 1
+            n = n >> 1
+
+        return cnt

valid-palindrome/daiyongg-kim.py

@@ -0,0 +1,4 @@
+class Solution:
+    def isPalindrome(self, s: str) -> bool:
+        s = re.sub(r'[^0-9A-Za-z]', '',s).lower()
+        return s == s[::-1]