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。

以下代码是用字母代替数字，便于查看

#include <iostream>
using namespace std;
typedef struct BiNode
{
struct BiNode* lchild,*rchild;
char data;
}BiNode,*BiTree;

void createTree(BiTree& root)
{
char data;
cout<<"please input"<<endl;
cin>>data;
if(data=='#')
return;
root = new BiNode;
root->data = data;
root->rchild= NULL;
root->lchild =NULL;
createTree(root->lchild);
createTree(root->rchild);
}
void printNodeByLay(BiTree root, int lay)
{
if(NULL==root)
return;
if(1==lay)
cout<<root->data<<" ";
printNodeByLay(root->lchild,lay-1);
printNodeByLay(root->rchild,lay-1);
}
int  printLay(BiTree root)
{
if(NULL==root)
return 0;
int l = printLay(root->lchild);
int r = printLay(root->rchild);
return l>r?(l+1):(r+1);
}
int main()
{
BiTree root=NULL;
createTree(root);
cout<<printLay(root)<<endl;
for(int i=1;i<=3;i++)
printNodeByLay(root,i);
return 0;
}