From 7cc71916e30985cc70927675ae37cf17e25ec717 Mon Sep 17 00:00:00 2001
From: Lam Haoyin <root@eatswap.org>
Date: Sat, 8 Jan 2022 01:03:33 +0800
Subject: [PATCH] add: 220108-CN

---
 2201/220108-CN.cpp  | 69 +++++++++++++++++++++++++++++++++++++++++++++
 2201/CMakeLists.txt |  2 +-
 CMakeLists.txt      |  1 +
 3 files changed, 71 insertions(+), 1 deletion(-)
 create mode 100644 2201/220108-CN.cpp

diff --git a/2201/220108-CN.cpp b/2201/220108-CN.cpp
new file mode 100644
index 0000000..e0310d5
--- /dev/null
+++ b/2201/220108-CN.cpp
@@ -0,0 +1,69 @@
+#include <vector>
+#include <iostream>
+#include <chrono>
+
+class Solution {
+public:
+	static std::vector<int> grayCode(const int n) {
+		std::vector<int> ret{0};
+		for (int i = 0; i < n; ++i) {
+			ret.insert(ret.end(), ret.rbegin(), ret.rend());
+			for (int j = 1 << i; j < (1 << (1 + i)); ++j)
+				ret[j] |= (1 << i);
+		}
+		return ret;
+	}
+};
+
+class SolutionOld {
+public:
+	static std::vector<int> grayCode(const int n) {
+		int lim = 1 << n, cur = 0;
+		std::vector<int> ret{0};
+		ret.reserve(lim);
+		int* const vis = new int[1 + (lim >> 5)]{0x1};
+		for (int i = 1; i < lim; ++i) {
+			for (int j = 0; j < n; ++j) {
+				if (!(vis[(cur ^ (1 << j)) >> 5] & (1 << ((cur ^ (1 << j)) & 0x1F)))) {
+					ret.push_back(cur ^= (1 << j));
+					vis[cur >> 5] |= (1 << (cur & 0x1F));
+					break;
+				}
+			}
+		}
+		delete[] vis;
+		return ret;
+	}
+};
+
+class Solution0ms {
+public:
+	static std::vector<int> grayCode(int n) {
+		std::vector<int> ans = {0, 1};
+		for (int i = 2; i <= n; i++) {
+			int x = (1 << (i - 1));
+			int idx = ans.size() - 1;
+			while (idx >= 0) {
+				int num = (ans[idx] + x);
+				ans.push_back(num);
+				idx--;
+			}
+		}
+		return ans;
+	}
+};
+
+int main() {
+	const int n = 30;
+	auto t1 = std::chrono::high_resolution_clock::now();
+	SolutionOld::grayCode(n);
+	auto t2 = std::chrono::high_resolution_clock::now();
+	Solution::grayCode(n);
+	auto t4 = std::chrono::high_resolution_clock::now();
+	Solution0ms::grayCode(n);
+	auto t5 = std::chrono::high_resolution_clock::now();
+	std::cout << "SolutionOld: " << std::chrono::duration_cast<std::chrono::milliseconds>(t2 - t1).count() << "ms" << std::endl;
+	std::cout << "Solution: " << std::chrono::duration_cast<std::chrono::milliseconds>(t4 - t2).count() << "ms" << std::endl;
+	std::cout << "Solution0ms: " << std::chrono::duration_cast<std::chrono::milliseconds>(t5 - t4).count() << "ms" << std::endl;
+	return 0;
+}
diff --git a/2201/CMakeLists.txt b/2201/CMakeLists.txt
index 9bcff76..98932c2 100644
--- a/2201/CMakeLists.txt
+++ b/2201/CMakeLists.txt
@@ -3,4 +3,4 @@ PROJECT(2201)
 
 SET(CMAKE_CXX_STANDARD 23)
 
-ADD_EXECUTABLE(2201 220107.cpp)
\ No newline at end of file
+ADD_EXECUTABLE(2201 220108-CN.cpp)
\ No newline at end of file
diff --git a/CMakeLists.txt b/CMakeLists.txt
index 4f3c99c..533e154 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -3,6 +3,7 @@ PROJECT(LeetCodeDaily)
 
 SET(CMAKE_CXX_STANDARD 23)
 
+# -Ofast -march=native -mtune=native -finline-functions -ffast-math -fomit-frame-pointer
 SET(CMAKE_CXX_FLAGS "-Wall")
 
 ADD_EXECUTABLE(LeetCodeDaily main.cpp)