From 61cd797e2891abb6a24bd623eb390544d46f61ff Mon Sep 17 00:00:00 2001
From: Eatswap <root@eatswap.org>
Date: Tue, 11 Apr 2023 19:12:26 +0800
Subject: [PATCH] add: 230411-CN

---
 cpp/2304/230411-CN.cpp  | 48 +++++++++++++++++++++++++++++++++++++++++
 cpp/2304/CMakeLists.txt |  2 +-
 2 files changed, 49 insertions(+), 1 deletion(-)
 create mode 100644 cpp/2304/230411-CN.cpp

diff --git a/cpp/2304/230411-CN.cpp b/cpp/2304/230411-CN.cpp
new file mode 100644
index 0000000..e64c9b6
--- /dev/null
+++ b/cpp/2304/230411-CN.cpp
@@ -0,0 +1,48 @@
+#include <string>
+
+/**
+ * 1041. Robot Bounded In Circle
+ *
+ * On an infinite plane, a robot initially stands at (0, 0) and faces north. Note that:
+ *
+ * The north direction is the positive direction of the y-axis.
+ * The south direction is the negative direction of the y-axis.
+ * The east direction is the positive direction of the x-axis.
+ * The west direction is the negative direction of the x-axis.
+ * The robot can receive one of three instructions:
+ *
+ * "G": go straight 1 unit.
+ * "L": turn 90 degrees to the left (i.e., anti-clockwise direction).
+ * "R": turn 90 degrees to the right (i.e., clockwise direction).
+ * The robot performs the instructions given in order, and repeats them forever.
+ *
+ * Return true if and only if there exists a circle in the plane such that the robot never leaves the circle.
+ *
+ * Refer: 220109.cpp
+ */
+
+class Solution {
+private:
+	// N, W, S, E
+	static const inline short dX[] = {0, -1, 0, 1};
+	static const inline short dY[] = {1, 0, -1, 0};
+public:
+	static bool isRobotBounded(const std::string&);
+};
+
+bool Solution::isRobotBounded(const std::string& instructions) {
+	const int n = instructions.size();
+	short X = 0, Y = 0, D = 0;
+	for (int i = 0; i < (n << 2); ++i) {
+		if (char ch = instructions[i % n]; ch == 'G') {
+			X += dX[D];
+			Y += dY[D];
+		} else D = (D + 1 + (ch & 3)) & 3;
+	}
+	return !(X | Y | D);
+}
+
+int main() {
+	Solution::isRobotBounded("LLGRL");
+	return 0;
+}
diff --git a/cpp/2304/CMakeLists.txt b/cpp/2304/CMakeLists.txt
index d9a8d0f..3e3d796 100644
--- a/cpp/2304/CMakeLists.txt
+++ b/cpp/2304/CMakeLists.txt
@@ -4,4 +4,4 @@ PROJECT(2304)
 SET(CMAKE_CXX_STANDARD 23)
 SET(CMAKE_EXPORT_COMPILE_COMMANDS true)
 
-ADD_EXECUTABLE(2304 230411.cpp)
+ADD_EXECUTABLE(2304 230411-CN.cpp)