分层遍历二叉树（编程之美3.10）

// 3_10.cpp : 定义控制台应用程序的入口点。
//

#include "stdafx.h"
#include <vector>

struct Node
{
int data;
Node * left;
Node * right;
};

int printByLevel(Node * root, int level)
{
if(!root || level < 0)
return 0;
if(level == 0)
{
printf("%d ",root->data);
return 1;
}
return printByLevel(root->left, level-1) + printByLevel(root->right, level-1);

}

//不使用queue的原因是不能区分每一层的结束，没法分行输出
void print(Node * root)
{
std::vector<Node*> vec;
vec.push_back(root);
int cur = 0;
int last = 1;
while(cur<vec.size())
{
last = vec.size();
while(cur < last)
{
printf("%d ", vec[cur]->data);
if(vec[cur]->left != NULL)
vec.push_back(vec[cur]->left);
if(vec[cur]->right != NULL)
vec.push_back(vec[cur]->right);
cur++;
}
printf("\n");
}
}

int _tmain(int argc, _TCHAR* argv[])
{
Node * root = new Node();
Node * n1 = new Node();
Node * n2 = new Node();
Node * n3 = new Node();

root->data = 0;
root->left = n1;
root->right = n2;
n1->left = NULL;
n1->right = NULL;
n2->left = n3;
n2->right = NULL;
n3->left = NULL;
n3->right = NULL;
n1->data = 1;
n2->data = 2;
n3->data = 3;

printByLevel(root,1);
printf("\n");
print(root);

return 0;
}