[Algorithms] 二叉树的递归遍历

2025-04-24 18:58:04   2025-04-24 18:58:04
Categories Algorithms BinaryTree
Tags

349 Words   |   2 Minutes

来源：代码随想录

LeetCode 144. 二叉树的前序遍历

LeetCode 145. 二叉树的后序遍历

LeetCode 94. 二叉树的中序遍历

前序

/**
 * Definition for a binary tree node.
 * struct TreeNode {
 *     int val;
 *     TreeNode *left;
 *     TreeNode *right;
 *     TreeNode() : val(0), left(nullptr), right(nullptr) {}
 *     TreeNode(int x) : val(x), left(nullptr), right(nullptr) {}
 *     TreeNode(int x, TreeNode *left, TreeNode *right) : val(x), left(left), right(right) {}
 * };
 */
class Solution {
public:
    void traversal(TreeNode *node, vector<int> &v) {
        if (node == nullptr) {
            return;
        }
        v.push_back(node->val);
        traversal(node->left, v);
        traversal(node->right, v);
    }

    vector<int> preorderTraversal(TreeNode* root) {
        vector<int> v;
        traversal(root, v);
        return v;
    }
};

---

中序

/**
 * Definition for a binary tree node.
 * struct TreeNode {
 *     int val;
 *     TreeNode *left;
 *     TreeNode *right;
 *     TreeNode() : val(0), left(nullptr), right(nullptr) {}
 *     TreeNode(int x) : val(x), left(nullptr), right(nullptr) {}
 *     TreeNode(int x, TreeNode *left, TreeNode *right) : val(x), left(left), right(right) {}
 * };
 */
class Solution {
public:
    void traversal(TreeNode *node, vector<int> &v) {
        if (node == nullptr) {
            return;
        }
        traversal(node->left, v);
        v.push_back(node->val);
        traversal(node->right, v);
    }

    vector<int> inorderTraversal(TreeNode* root) {
        vector<int> v;
        traversal(root, v);
        return v;
    }
};

---

后序

/**
 * Definition for a binary tree node.
 * struct TreeNode {
 *     int val;
 *     TreeNode *left;
 *     TreeNode *right;
 *     TreeNode() : val(0), left(nullptr), right(nullptr) {}
 *     TreeNode(int x) : val(x), left(nullptr), right(nullptr) {}
 *     TreeNode(int x, TreeNode *left, TreeNode *right) : val(x), left(left), right(right) {}
 * };
 */
class Solution {
public:
    void traversal(TreeNode *node, vector<int> &v) {
        if (node == nullptr) {
            return;
        }
        traversal(node->left, v);
        traversal(node->right, v);
        v.push_back(node->val);
    }

    vector<int> postorderTraversal(TreeNode* root) {
        vector<int> v;
        traversal(root, v);
        return v;
    }
};

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