Create smallest-number-with-all-set-bits.cpp

Author: kamyu104

C++/smallest-number-with-all-set-bits.cpp

@@ -0,0 +1,14 @@
+// Time:  O(1)
+// Space: O(1)
+
+// bit manipulation
+class Solution {
+public:
+    int smallestNumber(int n) {
+        const auto& bit_length = [](auto x) {
+            return (x ? std::__lg(x) : -1) + 1;
+        };
+
+        return (1 << bit_length(n)) - 1;
+    }
+};