counting bits solution

Author: yhkee0404

counting-bits/yhkee0404.swift

@@ -0,0 +1,9 @@
+class Solution {
+    func countBits(_ n: Int) -> [Int] {
+        var ans = Array(repeating: 0, count: n + 1) // S(n) = O(n)
+        for i in 1..<n+1 { // T(n) = O(n)
+            ans[i] = ans[i >> 1] + (i & 1)
+        }
+        return ans
+    }
+}