add: 220217-CN [C++]

2202/220217-CN.cpp

@@ -0,0 +1,39 @@
+#include <cstdio>
+#include <cstring>
+
+class Solution {
+private:
+	inline static constexpr int dX[] = {-2, -1, 1, 2, 2, 1, -1, -2};
+	inline static constexpr int dY[] = {1, 2, 2, 1, -1, -2, -2, -1};
+
+	inline static constexpr bool isValid(int n, int x, int y) {
+		return x >= 0 && y >= 0 && x < n && y < n;
+	}
+public:
+	inline static constexpr double knightProbability(int n, int k, int row, int column) {
+		double dp[25][25], dpNext[25][25];
+		for (int i = 0; i < n; ++i)
+			for (int j = 0; j < n; ++j)
+				dp[i][j] = 1.0;
+		for (int i = 0; i < k; ++i) {
+			for (int x = 0; x < n; ++x) {
+				for (int y = 0; y < n; ++y) {
+					dpNext[x][y] = 0.0;
+					for (int idx = 0; idx < 8; ++idx) {
+						if (isValid(n, x + dX[idx], y + dY[idx])) {
+							dpNext[x][y] += dp[x + dX[idx]][y + dY[idx]];
+						}
+					}
+					dpNext[x][y] /= 8.0;
+				}
+			}
+			std::memcpy(dp, dpNext, sizeof dp);
+		}
+		return dp[row][column];
+	}
+};
+
+int main() {
+	std::printf("%lf\n", Solution::knightProbability(3, 2, 0, 0));
+	return 0;
+}

2202/CMakeLists.txt

@@ -3,4 +3,4 @@ PROJECT(2202)
 
 SET(CMAKE_CXX_STANDARD 23)
 
-ADD_EXECUTABLE(2202 220217.cpp)
+ADD_EXECUTABLE(2202 220217-CN.cpp)