[LC] feat: 240824 counting bits

Author: HaJunYoo

counting-bits/hajunyoo.py

@@ -0,0 +1,34 @@
+class Solution1:
+    # time complexity: O(n)
+    # space complexity: O(1)
+    def countBits(self, n: int) -> List[int]:
+        list = [i for i in range(n + 1)]
+        result = [bin(num).count('1') for num in list]
+        return result
+
+class Solution2:
+    # time complexity: O(n * logn)
+    # space complexity: O(1)
+    def countBits(self, n: int) -> List[int]:
+
+        def count(num):
+            cnt = 0
+            while num:
+                cnt += num % 2
+                num //= 2
+            return cnt
+
+        res = [count(i) for i in range(n+1)]
+        return res
+
+class Solution3:
+    # time complexity: O(n)
+    # space complexity: O(1)
+    def countBits(self, n: int) -> List[int]:
+        res = [0] * (n + 1)
+        msb = 1
+        for i in range(1, n + 1):
+            if i == msb * 2:
+                msb *= 2
+            res[i] = res[i - msb] + 1
+        return res