Application of C++ recursive functions in search algorithms?

Recursive functions are used in search algorithms to explore tree-like data structures. Depth-first search uses a stack to explore nodes, while breadth-first search uses a queue to traverse layer by layer. In practical applications, such as finding files, recursive functions can be used to search for a given file in a specified directory.

C Application of recursive function in search algorithm

The recursive function is a special method that calls itself inside the function function. This approach is particularly useful when solving problems with tree-like data structures such as searching and traversing.

Depth First Search (DFS)

The depth first search algorithm (DFS) uses a stack to explore nodes, searching in depth through all possible branches of a node, and then Backtrack to the previous node of this node and continue exploring the next branch until the entire tree is traversed.

// 执行深度优先搜索
void DFS(Node* node) {
  // 访问当前节点
  Visit(node);

  // 递归遍历所有子节点
  for (Node* child : node->children) {
    DFS(child);
  }
}

Breadth-First Search (BFS)

The breadth-first search algorithm (BFS) uses a queue to explore nodes and traverse the tree in hierarchical order. It adds all nodes in the current layer to the queue and then accesses these nodes in sequence. After visiting all the child nodes of a node, continue to the next level.

// 执行广度优先搜索
void BFS(Node* root) {
  // 创建队列并添加根节点
  Queue<Node*> queue;
  queue.push(root);

  // 当队列不为空时，继续遍历
  while (!queue.empty()) {
    // 取出队首节点
    Node* node = queue.front();
    queue.pop();

    // 访问当前节点
    Visit(node);

    // 将子节点添加至队列
    for (Node* child : node->children) {
      queue.push(child);
    }
  }
}

Practical case: Find files

Suppose there is a file system in which each file or directory can contain subfiles and subdirectories. We can use recursive functions to search for a given file.

// 在指定目录中搜索文件
bool SearchFile(string directory, string filename) {
  // 获取当前目录的所有子文件和子目录
  vector<string> entries = GetEntries(directory);

  // 遍历子项
  for (string entry : entries) {
    // 如果文件是目录，则递归搜索
    if (IsDirectory(entry)) {
      if (SearchFile(entry, filename)) {
        return true;
      }
    } else {
      // 如果文件是目标文件，则返回 true
      if (entry == filename) {
        return true;
      }
    }
  }

  // 如果未找到文件，则返回 false
  return false;
}

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