solve: countingBits

Author: yolophg

counting-bits/yolophg.py

@@ -0,0 +1,18 @@
+# Time Complexity: O(n) -> iterate from 1 to n, updating arr[] in O(1) for each i.
+# Space Complexity: O(n) -> store results in an array of size (n+1).
+
+class Solution:
+    def countBits(self, n: int) -> List[int]:
+        # make an array of size (n+1), initialized with 0s.
+        arr = [0] * (n + 1)  
+        
+        # loop from 1 to n
+        for i in range(1, n + 1):  
+            if i % 2 == 0:
+                # even number -> same count as i//2
+                arr[i] = arr[i // 2]  
+            else:
+                # odd number -> one more bit than i//2
+                arr[i] = arr[i // 2] + 1  
+        
+        return arr