【练习】输入一颗二元树，从上往下按层打印树的每个结点，同一层中按照从左往右的顺序打印

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/* 题目：输入一颗二元树，从上往下按层打印树的每个结点，同一层中按照从左往右的顺序打印。
例如输入

8
/ \
6 10
/\ /\
5 7 9 11

输出8 6 10 5 7 9 11。

思路：
广度优先遍历

deque(STL)*/
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#include <iostream>
#include <deque>
using namespace std;

struct BTree
{
BTree* pLeft;
BTree* pRight;
int value;
};
void InsertBTree(BTree* &pRoot, int n)
{
if (!pRoot)
{
pRoot= new BTree;
pRoot->pLeft=NULL;
pRoot->pRight=NULL;
pRoot->value=n;
}
else
{
if (n>pRoot->value)
{
InsertBTree(pRoot->pRight,n);
}
if (n<pRoot->value)
{
InsertBTree(pRoot->pLeft,n);
}
if (n==pRoot->value)
{
cout<< "repeated insertion" <<endl;
}
}
}
void VisitByLevel(BTree* pRoot)
{
if (!pRoot)
{
return ;
}
deque<BTree*> BTDeque;
BTDeque.push_back(pRoot);
while (BTDeque.size())
{
BTree* p=BTDeque.front();
cout<<p->value<< "\t" ;
BTDeque.pop_front();
if (p->pLeft)
{
BTDeque.push_back(p->pLeft);
}
if (p->pRight)
{
BTDeque.push_back(p->pRight);
}
}
}
int main()
{
BTree* pRoot=NULL;
InsertBTree(pRoot,8);
InsertBTree(pRoot,6);
InsertBTree(pRoot,10);
InsertBTree(pRoot,5);
InsertBTree(pRoot,7);
InsertBTree(pRoot,9);
InsertBTree(pRoot,11);
VisitByLevel(pRoot);
return 0;
}