add: 220519 [cpp]

cpp/2205/220519.cpp

@@ -0,0 +1,48 @@
+#include <vector>
+#include <functional>
+#include <cstdio>
+
+/**
+ * 329. Longest Increasing Path in a Matrix
+ * Given an m x n integers matrix, return the length of the longest increasing path in matrix.
+ * From each cell, you can either move in four directions: left, right, up, or down. You may not move diagonally or move outside the boundary (i.e., wrap-around is not allowed).
+ */
+
+class Solution {
+private:
+	inline static int dX[] = {0, 1, 0, -1};
+	inline static int dY[] = {1, 0, -1, 0};
+
+public:
+	static int longestIncreasingPath(const std::vector<std::vector<int>>& matrix) {
+		const int m = matrix.size(), n = matrix.front().size();
+
+		int* dp = new int[m * n]{};
+		std::function<int(int)> d = [&](int id) {
+			if (dp[id])
+				return dp[id];
+
+			const int x = id / n, y = id % n;
+			// 4 directions
+			int ans = 1;
+			for (int i = 0; i < 4; ++i) {
+				if (x + dX[i] < 0 || x + dX[i] >= m || y + dY[i] < 0 || y + dY[i] >= n || matrix[x + dX[i]][y + dY[i]] <= matrix[x][y])
+					continue;
+				ans = std::max(ans, 1 + d((x + dX[i]) * n + (y + dY[i])));
+			}
+			return dp[id] = ans;
+		};
+
+		int ret = 0;
+		for (int i = 0; i < m * n; ++i)
+			ret = std::max(ret, d(i));
+
+		delete[] dp;
+		return ret;
+	}
+};
+
+int main() {
+	std::printf("%d\n", Solution::longestIncreasingPath({{9,9,4},{6,6,8},{2,1,1}}));
+	return 0;
+}

cpp/2205/CMakeLists.txt

@@ -3,4 +3,4 @@ PROJECT(2205)
 
 SET(CMAKE_CXX_STANDARD 23)
 
-ADD_EXECUTABLE(2205 220519-CN.cpp)
+ADD_EXECUTABLE(2205 220519.cpp)