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

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/**
* File: binary_tree_bfs.cpp
* Created Time: 2022-11-25
* Author: Krahets (krahets@163.com)
*/
#include "../utils/common.hpp"
/* 层序遍历 */
vector<int> levelOrder(TreeNode *root) {
// 初始化队列,加入根节点
queue<TreeNode *> queue;
queue.push(root);
// 初始化一个列表,用于保存遍历序列
vector<int> vec;
while (!queue.empty()) {
TreeNode *node = queue.front();
queue.pop(); // 队列出队
vec.push_back(node->val); // 保存节点值
if (node->left != nullptr)
queue.push(node->left); // 左子节点入队
if (node->right != nullptr)
queue.push(node->right); // 右子节点入队
}
return vec;
}
/* 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);
/* 层序遍历 */
vector<int> vec = levelOrder(root);
cout << endl << "层序遍历的节点打印序列 = ";
printVector(vec);
return 0;
}