[chordpli] Week3 Solutions (#1808)

Author: chordpli

combination-sum/chordpli.py

@@ -0,0 +1,29 @@
+from typing import List
+
+
+class Solution:
+    def combinationSum(self, candidates: List[int], target: int) -> List[List[int]]:
+        result = []
+        candidates.sort()
+        self.__backtrack__(candidates, 0, target, result, [])
+        return result
+
+    def __backtrack__(self, candidates: List[int], current_idx: int, target: int, result: List[List[int]],
+                      current_arr: List[int]):
+        if current_idx >= len(candidates):
+            return
+
+        add_value = sum(current_arr) + candidates[current_idx]
+
+        if add_value == target:
+            current_arr.append(candidates[current_idx])
+            result.append(current_arr.copy())
+            current_arr.pop()
+
+        if add_value > target:
+            return self.__backtrack__(candidates, current_idx + 1, target, result, current_arr)
+
+        current_arr.append(candidates[current_idx])
+        self.__backtrack__(candidates, current_idx, target, result, current_arr)
+        current_arr.pop()
+        self.__backtrack__(candidates, current_idx + 1, target, result, current_arr)

number-of-1-bits/chordpli.py

@@ -0,0 +1,3 @@
+class Solution:
+    def hammingWeight(self, n: int) -> int:
+        return bin(n).count('1')

valid-palindrome/chordpli.py

@@ -0,0 +1,13 @@
+import re
+
+
+class Solution:
+    def isPalindrome(self, s: str) -> bool:
+        lower_s = s.lower()
+        lower_eng_str = re.sub(r"[^a-z0-9]", "", lower_s)
+        reverse_str = lower_eng_str[::-1]
+
+        if lower_eng_str == reverse_str:
+            return True
+
+        return False