add: 220516 [cpp]

cpp/2205/220516.cpp

@@ -0,0 +1,52 @@
+#include <vector>
+#include <iostream>
+
+/**
+ * 1091. Shortest Path in Binary Matrix
+ * Given an n x n binary matrix grid, return the length of the shortest clear path in the matrix. If there is no clear path, return -1.
+ *
+ * A clear path in a binary matrix is a path from the top-left cell (i.e., (0, 0)) to the bottom-right cell (i.e., (n - 1, n - 1)) such that:
+ *
+ * All the visited cells of the path are 0.
+ * All the adjacent cells of the path are 8-directionally connected (i.e., they are different and they share an edge or a corner).
+ * The length of a clear path is the number of visited cells of this path.
+ */
+
+class Solution {
+public:
+	static int shortestPathBinaryMatrix(const std::vector<std::vector<int>>& grid) {
+		const int n = grid.size();
+		if (grid[0][0])
+			return -1;
+
+		std::vector<bool> vis(n * n);
+		int queue[10003]; // Array emulated
+		int front = 0, rear = 1; // queue
+
+		while (rear > front) {
+			int pos = queue[front++];
+			// pos = x * n + y;
+			int depth = pos >> 16;
+			pos &= 0xFFFF;
+			int y = pos % n, x = pos / n;
+
+			if (x == n - 1 && y == n - 1) {
+				return depth + 1;
+			}
+
+			for (int i = -1; i <= 1; ++i) {
+				for (int j = -1; j <= 1; ++j) {
+					if ((!i && !j) || (x + i < 0 || x + i >= n || y + j < 0 || y + j >= n) || vis[pos + j + i * n] || grid[x + i][y + j])
+						continue;
+					vis[pos + j + i * n] = true;
+					queue[rear++] = (pos + j + i * n) | ((1 + depth) << 16);
+				}
+			}
+		}
+		return -1;
+	}
+};
+
+int main() {
+	std::cout << Solution::shortestPathBinaryMatrix({{0,0,0},{1,1,0},{1,1,0}});
+}

cpp/2205/CMakeLists.txt

@@ -3,4 +3,4 @@ PROJECT(2205)
 
 SET(CMAKE_CXX_STANDARD 23)
 
-ADD_EXECUTABLE(2205 220515.cpp)
+ADD_EXECUTABLE(2205 220516.cpp)