From a16ad4990037c4488158762221cbe2c719e37642 Mon Sep 17 00:00:00 2001
From: Xu Shaohua <shaohua@biofan.org>
Date: Wed, 25 Sep 2024 11:29:11 +0800
Subject: [PATCH] od: Add cpp impl to moving area

---
 src/od/2024e200/moving-area-of-robot/Makefile |  6 ++
 src/od/2024e200/moving-area-of-robot/index.md | 14 ++-
 .../moving-area-of-robot/solution.cpp         | 89 +++++++++++++++++++
 3 files changed, 108 insertions(+), 1 deletion(-)
 create mode 100644 src/od/2024e200/moving-area-of-robot/Makefile
 create mode 100644 src/od/2024e200/moving-area-of-robot/solution.cpp

diff --git a/src/od/2024e200/moving-area-of-robot/Makefile b/src/od/2024e200/moving-area-of-robot/Makefile
new file mode 100644
index 00000000..98586cd8
--- /dev/null
+++ b/src/od/2024e200/moving-area-of-robot/Makefile
@@ -0,0 +1,6 @@
+
+build: solution.cpp
+	g++ -g solution.cpp -o solution
+
+clean:
+	rm solution
diff --git a/src/od/2024e200/moving-area-of-robot/index.md b/src/od/2024e200/moving-area-of-robot/index.md
index 8a2bc69b..741b162a 100644
--- a/src/od/2024e200/moving-area-of-robot/index.md
+++ b/src/od/2024e200/moving-area-of-robot/index.md
@@ -62,4 +62,16 @@
 
 ## 题解
 
-使用 广度优先搜索 BFS 求得最大的连接节点数.
\ No newline at end of file
+使用 广度优先搜索 BFS 求得最大的连接节点数.
+
+### Python
+
+```python
+{{#include solution.py:6:}}
+```
+
+### C++
+
+```cpp
+{{#include solution.cpp:5:}}
+```
diff --git a/src/od/2024e200/moving-area-of-robot/solution.cpp b/src/od/2024e200/moving-area-of-robot/solution.cpp
new file mode 100644
index 00000000..b5ceae07
--- /dev/null
+++ b/src/od/2024e200/moving-area-of-robot/solution.cpp
@@ -0,0 +1,89 @@
+// Copyright (c) 2024 Xu Shaohua <shaohua@biofan.org>. All rights reserved.
+// Use of this source is governed by General Public License that can be found
+// in the LICENSE file.
+
+#include <cassert>
+
+#include <array>
+#include <iostream>
+#include <string>
+#include <vector>
+
+int dfs_visit(const std::vector<std::vector<int>>& grid,
+              std::vector<std::vector<bool>>& visited,
+              int x, int y, int rows, int columns) {
+  if (visited[x][y]) {
+    return 0;
+  }
+  // 先标记当前节点状态
+  int move_range = 1;
+  visited[x][y] = true;
+
+  const std::array<std::array<int, 2>, 4> directions = 
+    {std::array<int, 2>{1, 0}, {-1, 0}, {0, 1}, {0, -1}};
+  // 开始准备向四个方向访问
+  for (const auto dir : directions) {
+    int x1 = x + dir[0];
+    int y1 = y + dir[1];
+    // 判断新的节点是否满足条件
+    // 1. 在矩形范围内移动
+    // 2. 新的节点未被访问过
+    // 3. 两个节点上的值相差小于等于1
+
+    if (0 <= x1 && x1 < rows && 0 <= y1 && y1 < columns && !visited[x1][y1] && 
+        std::abs(grid[x][y] - grid[x1][y1]) <= 1) {
+      // 递归访问新的节点
+      move_range += dfs_visit(grid, visited, x1, y1, rows, columns);
+    }
+  }
+
+  // 返回移动次数
+  return move_range;
+}
+
+void solution() {
+  // 读取行与列
+  int rows = 0;
+  int columns = 0;
+  std::cin >> rows >> columns;
+  assert(rows > 0 && columns > 0);
+  // 换行符
+  std::string line;
+  std::getline(std::cin, line);
+
+  // 读取二维数组
+  std::vector<std::vector<int>> grid;
+  for (int row = 0; row < rows; ++row) {
+    std::vector<int> nums(columns);
+    for (int& num : nums) {
+      std::cin >> num;
+    }
+    grid.emplace_back(nums);
+    // 换行符
+    std::getline(std::cin, line);
+  }
+
+  // 标记已经访问过了的节点
+  std::vector<std::vector<bool>> visited(rows, std::vector<bool>(columns, false));
+
+  int max_move_range = 0;
+
+  // 接下来遍历所有的节点, 找到最大的访问范围.
+  for (int row = 0; row < rows; ++row) {
+    for (int column = 0; column < columns; ++column) {
+      // 如果该节点已经访问过, 就忽略
+      if (!visited[row][column]) {
+        const int move_range = dfs_visit(grid, visited, row, column, rows, columns);
+        max_move_range = std::max(max_move_range, move_range);
+      }
+    }
+  }
+
+  // 打印结果
+  std::cout << max_move_range << std::endl;
+}
+
+int main() {
+  solution();
+  return 0;
+}