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hello-algo/codes/cpp/chapter_tree/binary_tree_dfs.cpp

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1.6 KiB

/**
* File: binary_tree_dfs.cpp
* Created Time: 2022-11-25
* Author: krahets (krahets@163.com)
*/
#include "../utils/common.hpp"
// 初始化列表,用于存储遍历序列
vector<int> vec;
/* 前序遍历 */
void preOrder(TreeNode *root) {
if (root == nullptr)
return;
// 访问优先级:根节点 -> 左子树 -> 右子树
vec.push_back(root->val);
preOrder(root->left);
preOrder(root->right);
}
/* 中序遍历 */
void inOrder(TreeNode *root) {
if (root == nullptr)
return;
// 访问优先级:左子树 -> 根节点 -> 右子树
inOrder(root->left);
vec.push_back(root->val);
inOrder(root->right);
}
/* 后序遍历 */
void postOrder(TreeNode *root) {
if (root == nullptr)
return;
// 访问优先级:左子树 -> 右子树 -> 根节点
postOrder(root->left);
postOrder(root->right);
vec.push_back(root->val);
}
/* Driver Code */
int main() {
/* 初始化二叉树 */
// 这里借助了一个从数组直接生成二叉树的函数
TreeNode *root = vectorToTree(vector<int>{1, 2, 3, 4, 5, 6, 7});
cout << endl << "初始化二叉树\n" << endl;
printTree(root);
/* 前序遍历 */
vec.clear();
preOrder(root);
cout << endl << "前序遍历的节点打印序列 = ";
printVector(vec);
/* 中序遍历 */
vec.clear();
inOrder(root);
cout << endl << "中序遍历的节点打印序列 = ";
printVector(vec);
/* 后序遍历 */
vec.clear();
postOrder(root);
cout << endl << "后序遍历的节点打印序列 = ";
printVector(vec);
return 0;
}