Reverse bits (#211)

* add reverse bits

* impl reverse bits

leetcode-cc/ReverseBits.hpp

@@ -0,0 +1,40 @@
+#include "TestHelper.h"
+#include "problem.h"
+#include "solution.h"
+
+using namespace std;
+
+IMPLEMENT_PROBLEM_CLASS(PReverseBits, 190, DIFFI_EASY, TOPIC_ALGORITHMS,
+                        "Reverse Bits",
+                        "Reverse bits of a given 32 bits unsigned integer.",
+                        {"Bit"});
+
+class SReverseBits : public ISolution {
+ public:
+  size_t problemId() const override { return 190; }
+  string name() const override {
+    return ("Solution for " + string("Reverse Bits"));
+  }
+  string location() const override { return __FILE_NAME__; }
+  int test() const override {
+    return testHelper<uint32_t, uint32_t>(
+        {0b00000010100101000001111010011100,
+         0b11111111111111111111111111111101},
+        {0b00111001011110000010100101000000,
+         0b10111111111111111111111111111111},
+        [this](auto input) { return this->reverseBits(input); });
+  };
+  int benchmark() const override { return 0; }
+
+ private:
+  uint32_t reverseBits(uint32_t n) const {
+    const int N = 32;
+    uint32_t res = 0;
+
+    for (int i = 0; i < N; i++) {
+      res = (res << 1) + ((n >> i) & 0x1);
+    }
+
+    return res;
+  }
+};

runtime-cc/src/registration.cc

@@ -87,6 +87,7 @@
 #include "../leetcode-cc/ReorderList.hpp"
 #include "../leetcode-cc/RepeatedDNASeq.hpp"
 #include "../leetcode-cc/RestoreIpAddresses.hpp"
+#include "../leetcode-cc/ReverseBits.hpp"
 #include "../leetcode-cc/ReverseLinkedListII.hpp"
 #include "../leetcode-cc/ReverseNodesinKGroup.hpp"
 #include "../leetcode-cc/ReverseWords.hpp"
@@ -795,5 +796,10 @@ const int registerAll(std::shared_ptr<Container> handle) {
   handle->registerSolution(
       []() -> ArcSolution { return std::make_shared<SRotateArray>(); });
 
+  handle->registerProblem(
+      []() -> ArcProblem { return std::make_shared<PReverseBits>(); });
+  handle->registerSolution(
+      []() -> ArcSolution { return std::make_shared<SReverseBits>(); });
+
   return 0;
 }