從上往下打印二叉樹

從上往下打印出二叉樹的每個結點，同一層按照從左到右的順序打印

#include <iostream>
#include <deque>
using namespace std;

struct BinaryTreeNode
{
int data;
struct BinaryTreeNode *lchild;
struct BinaryTreeNode *rchild;
};

typedef struct BinaryTreeNode BinTreeNode;

//先序構造二叉樹
BinTreeNode* preOrderCreateTree(BinTreeNode *head)
{
int tmp;
cin >> tmp;
if (tmp == 0)
head = NULL;
else
{
head = new BinTreeNode;
head->data = tmp;
head->lchild = preOrderCreateTree(head->lchild);
head->rchild = preOrderCreateTree(head->rchild);
}

return head;
}

//先序遍歷二叉樹
void preVisitTree(const BinTreeNode *head)
{
if (head == NULL)
return;

cout << head->data;
preVisitTree(head->lchild);
preVisitTree(head->rchild);
}

void freeTree(BinTreeNode *head)
{
if (head == NULL)
return;

freeTree(head->lchild);
freeTree(head->rchild);
delete head;
}

void printOrderByLayer(const BinTreeNode *head)
{
if (head == NULL)
return;

deque<const BinTreeNode*> myDeque;
myDeque.push_back(head);
while (myDeque.size() > 0)
{
const BinTreeNode *tmp = myDeque.front();
myDeque.pop_front();
cout << tmp->data;
if (tmp->lchild)
myDeque.push_back(tmp->lchild);
if (tmp->rchild)
myDeque.push_back(tmp->rchild);
}
}

int main()
{
BinTreeNode *root = preOrderCreateTree(root);
preVisitTree(root);
cout << endl;
printOrderByLayer(root);
cout << endl;
freeTree(root);
return 0;
}

二叉樹的常見問題及其解決程序 http://www.linuxidc.com/Linux/2013-04/83661.htm

【遞歸】二叉樹的先序建立及遍歷 http://www.linuxidc.com/Linux/2012-12/75608.htm

在JAVA中實現的二叉樹結構 http://www.linuxidc.com/Linux/2008-12/17690.htm

【非遞歸】二叉樹的建立及遍歷 http://www.linuxidc.com/Linux/2012-12/75607.htm

二叉樹遞歸實現與二重指針 http://www.linuxidc.com/Linux/2013-07/87373.htm

二叉樹先序中序非遞歸算法 http://www.linuxidc.com/Linux/2014-06/102935.htm

輕松搞定面試中的二叉樹題目 http://www.linuxidc.com/linux/2014-07/104857.htm