c++实现二叉树后序遍历搜索节点并输出路径

二叉树的后序遍历是先遍历左子树，再遍历右子树，最后遍历根节点。因此，在搜索节点时也需要先递归遍历左子树和右子树，最后才能判断当前节点是否为目标节点。

以下是一个示例代码：

#include<iostream>
#include<vector>

using namespace std;

struct TreeNode {
    int val;
    TreeNode* left;
    TreeNode* right;
    TreeNode(int x) : val(x), left(NULL), right(NULL) {}
};

bool postorderTraversal(TreeNode* root, int target, vector<int>& path) {
    if (root == NULL) return false;  // 当前节点为空，返回false
    bool found = false;
    if (root->left) found = postorderTraversal(root->left, target, path);  // 递归遍历左子树
    if (root->right) found = postorderTraversal(root->right, target, path) || found;  // 递归遍历右子树
    if (root->val == target) found = true;  // 当前节点为目标节点，将found设置为true
    if (found) path.push_back(root->val);  // 如果找到目标节点，则将当前节点的值添加到路径中
    return found;
}

int main() {
    // 构造一棵二叉树
    TreeNode* root = new TreeNode(5);
    root->left = new TreeNode(3);
    root->right = new TreeNode(8);
    root->left->left = new TreeNode(2);
    root->left->right = new TreeNode(4);
    root->right->left = new TreeNode(7);
    root->right->right = new TreeNode(9);

    int target = 7;
    vector<int> path;
    bool found = postorderTraversal(root, target, path);
    if (found) {
        cout << "Path to node " << target << ": ";
        for (int i = path.size() - 1; i >= 0; i--) {
            cout << path[i] << " ";
        }
        cout << endl;
    } else {
        cout << "Node " << target << " not found." << endl;
    }

    return 0;
}

在以上代码中，`postorderTraversal`函数返回一个bool值，表示是否找到目标节点。如果找到，则将路径上的节点值添加到`path`向量中。最后，根据`path`向量输出路径。