编程之美读书笔记---分层遍历二叉树

#include <iostream>
#include <cstring>
#include <vector>
using namespace std;
struct node{
int data;
node* left;
node* right;
};
void creattree(node* &root)
{
root=new node;
root->data=1;
node* t2=new node;
t2->data=2;
root->left=t2;
node* t3=new node;
t3->data=3;
root->right=t3;
node* t4=new node;
t4->data=4;
t2->left=t4;
node* t5=new node;
t5->data=5;
t2->right=t5;
node* t6=new node;
t6->data=6;
t3->left=NULL;
t3->right=t6;
t6->left=t6->right=NULL;
t4->left=t4->right=NULL;
node* t7=new node;
t7->data=7;
t7->left=t7->right=NULL;
t5->left=t7;
node* t8=new node;
t8->data=8;
t8->left=t8->right=NULL;
t5->right=t8;
}
int printatlevel(node* root,int level)
{
if(!root||level<0)return 0;
if(level==0){
cout<<root->data<<" ";
return 1;
}
return printatlevel(root->left,level-1)+printatlevel(root->right,level-1);
}
void printbylevel(node* root)
{
for(int level=0;;level++)
{
if(!printatlevel(root,level))
break;
cout<<endl;
}
}
void destroy(node* root)
{
if(root->left==NULL&&root->right==NULL){
delete root;
return ;
}
if(root->left)destroy(root->left);
if(root->right)destroy(root->right);
delete root;
}
void print_new(node * root)
{
if(root==NULL)
return ;
vector<node*> vec;
vec.push_back(root);
int cur=0,last=1;
while(cur<vec.size())
{
last=vec.size();
while(cur<last)
{
cout<<vec[cur]->data<<" ";
if(vec[cur]->left)
vec.push_back(vec[cur]->left);
if(vec[cur]->right)
vec.push_back(vec[cur]->right);
cur++;
}
cout<<endl;
}
}
int main()
{
node *root;
creattree(root);
//printatlevel(root,1);
//printbylevel(root);
print_new(root);
destroy(root);      //回收由new分配的内存
return 0;
}