题目

按层遍历一棵多叉树，输出层号和节点

代码

#include <iostream>
#include <vector>
#include <memory>
#include <queue>

class TreeNode 
{
public:
    TreeNode(int num) : num_(num) {};
    TreeNode(const TreeNode& rhs) = default;
    ~TreeNode() = default;

    int getNum() const { return num_; }
    void addChild(std::shared_ptr<TreeNode>& child) { children.push_back(child); }
    void addChild(std::shared_ptr<TreeNode>&& child) { children.push_back(child); }
    auto getChild() const { return children; }

private:
    int num_;
    std::vector<std::shared_ptr<TreeNode>> children;
};

void layer(std::shared_ptr<TreeNode>& root) 
{
    typedef std::pair<int, std::shared_ptr<TreeNode>> PIT;
    std::queue<PIT> qe;
    qe.push({1, root});
    while (qe.size()) 
    {
        auto ele = qe.front();
        qe.pop();
        std::cout << ele.first << ' ' << ele.second->getNum() << '\n';

        for (auto &cld : ele.second->getChild()) 
        {
            qe.push({ele.first + 1, cld});
        }
    }
}

int main() 
{
    auto root = std::make_shared<TreeNode>(1);

    root->addChild(std::make_shared<TreeNode>(2));
    root->addChild(std::make_shared<TreeNode>(3));
    root->addChild(std::make_shared<TreeNode>(4));
    layer(root);

    return 0;

}