剑指Offer21 二叉树的层序遍历

/*************************************************************************
    > File Name: 21_PrintTreeTopToBottom.cpp
    > Author: Juntaran
    > Mail: JuntaranMail@gmail.com
    > Created Time: 2016年08月30日 星期二 20时24分53秒
 ************************************************************************/

#include <stdio.h>
#include <stdlib.h>
#include <malloc.h>
#include <bits/stdc++.h>

using namespace std;

// 二叉树结构体
struct TreeNode
{
    int val;
    TreeNode* left;
    TreeNode* right;
};

// 层序遍历
void PrintTreeTopToBottom(TreeNode* root)
{
    if (root == NULL)
        return;
    
    vector<TreeNode*> vec;
    vec.push_back(root);
    
    int cur = 0;
    while (cur < vec.size())
    {
        printf("%d ", vec[cur]->val);
        if (vec[cur]->left)
            vec.push_back(vec[cur]->left);
        if (vec[cur]->right)
            vec.push_back(vec[cur]->right);
        ++cur;
    }
    printf("
");
}

TreeNode* createTree()
{
    TreeNode* root = (TreeNode*)malloc(sizeof(TreeNode));
    root->val = 8;
    root->left = (TreeNode*)malloc(sizeof(TreeNode));
    root->left->val = 8;
    root->right = (TreeNode*)malloc(sizeof(TreeNode));
    root->right->val = 7;
    root->right->left = NULL;
    root->right->right = NULL;
    root->left->left = (TreeNode*)malloc(sizeof(TreeNode));
    root->left->left->val = 9;
    root->left->left->left = NULL;
    root->left->left->right = NULL;
    root->left->right = (TreeNode*)malloc(sizeof(TreeNode));
    root->left->right->val = 2;
    root->left->right->left = (TreeNode*)malloc(sizeof(TreeNode));
    root->left->right->left->val = 4;
    root->left->right->left->left = NULL;
    root->left->right->left->right = NULL;
    root->left->right->right = (TreeNode*)malloc(sizeof(TreeNode));
    root->left->right->right->val = 7;
    root->left->right->right->left = NULL;
    root->left->right->right->right = NULL;
    
    return root;
}

int main()
{
    TreeNode* test = createTree();
    PrintTreeTopToBottom(test);
}