树的层序遍历

1.基本思路

层序遍历的基本思路就是，
1.根节点入队列。
2.根节点出队，同时将根节点左儿子和右儿子入队
3.结点出队，同时将该节点的左儿子和右儿子入队
4.重复3直到队列为空

2.算法实现

void layerprint(struct TreeNode* r)
{
	struct queue q1;		//创建队列
	q1.s=&q1.node[0];		//初始化队列
	q1.e=&q1.node[0];
	struct TreeNode* p;		//临时结点指针
	in(&q1,r);				//根节点入队
	while(q1.e!=q1.s)		//判断队列是否为空
	{
		p = out(&q1);			//出队
		printf("%d ",p->data);		//访问结点
		if(p->left !=NULL)			
			in(&q1,p->left);		//左儿子入队
		if(p->right!=NULL)
			in(&q1,p->right);		//右儿子入队
	}		
}

3.完整代码

//main.c
#include<stdio.h>
#include "fun.c"
struct queue
{
	struct TreeNode node[100];
	struct TreeNode* s;
	struct TreeNode* e;
};
struct stack
{
	struct TreeNode node[100];
	struct TreeNode *top;
};
struct TreeNode* pop(struct stack* a)
{
	struct TreeNode* tmp =a->top;//printf("%d",*a->top);
	a->top--;
	return tmp;
	
}
int isEmpty(struct stack* a)
{
	if(a->top==&a->node[0])
		return 1;
	else 
		return 0;
}
void push(struct stack* a,struct TreeNode *node)
{
	a->top++;
	a->top->data = node->data;
	a->top->left = node->left;
	a->top->right = node->right;

}
void PrePrint(struct TreeNode *r)
{
	struct stack stack1;
	stack1.top = &stack1.node[0];
	struct TreeNode *p =r;
	while(p||!isEmpty(&stack1))
	{
		if(p!=NULL)
		{
			printf("%d ",p->data);
			push(&stack1,p);
			p = p->left;
		}
		else
		{
			p=pop(&stack1);
			p=p->right;
		}
	}
}
	



	/*while(p!=NULL)
	{
		//printf("%d ",p->data);
		if(p->left!=NULL)
		{
			printf("%d ",p->data);
			push(&stack1,p);	
			p=p->left;
		}
		else 
		{
			if(p->right!=NULL)
				p=p->right;
			printf("%d ",p->data);
			struct TreeNode* tmp;
			tmp = pop(&stack1);
			while(tmp->right==NULL)
			{tmp = pop(&stack1);}			
			p = tmp->right;
		}
		
	}	//push(&stack1,r);
	//pop()*/
/*void layerprint(struct TreeNode* r)
{
	queue q1;
	q1.s=&q1.node[0];
	q1.e=&q1.node[0];
}*/
void in(struct queue* a,struct TreeNode* b)
{
	*a->e=*b;
	//*a->e->left = *b->left;
	//*a->e->right =*b->right;
	a->e++;	
}
struct TreeNode* out(struct queue* a)
{
	struct TreeNode *tmp=(struct TreeNode*)malloc(sizeof(struct TreeNode));
	*tmp = *a->s;
	a->s++;
	return tmp;
}
void layerprint(struct TreeNode* r)
{
	struct queue q1;
	q1.s=&q1.node[0];
	q1.e=&q1.node[0];
	struct TreeNode* p;
	in(&q1,r);
	while(q1.e!=q1.s)
	{
		p = out(&q1);
		printf("%d ",p->data);
		if(p->left !=NULL)
			in(&q1,p->left);
		if(p->right!=NULL)
			in(&q1,p->right);
	}
	
}


int main()
{
	//struct stack stack1;
	//stack1.top = &stack1.node[0];
	int max;
	printf("input the num:");
	scanf("%d",&max);
	//printf("please input 6 num
 ");
	struct TreeNode *r;
	r=initTree();
	int i=0;
	for(;i<max-1;i++)
		createTree(r);
	//PrePrint(r);
	layerprint(r);
	return 0;
}

\fun.文件内容
#include<stdio.h>
#include<stdlib.h>
struct TreeNode
{
	int data;
	struct TreeNode* left;
	struct TreeNode* right;
}node;
struct TreeNode* initTree()
{
	struct TreeNode* r = (struct TreeNode* )malloc(sizeof(struct TreeNode));
	r->left = NULL;
	r->right =NULL;
	int num;
	scanf("%d",&num);
	r->data = num;
	return r;
}
void createTree(struct TreeNode* r)
{
	struct TreeNode *tmp = r;
	struct TreeNode *p ;
	int num;
	scanf("%d",&num);
	struct TreeNode *a = (struct TreeNode*)malloc(sizeof(struct TreeNode));
	a->left = NULL;
	a->right = NULL;
	a->data = num;
	while(tmp!=NULL)
	{
		if(num >= tmp->data)
		{
			p=tmp;
			tmp = tmp->right;			
		}
		else
		{
			p=tmp;
			tmp = tmp->left;
		}
	}
	if(a->data>=p->data)
	{
		p->right = a;
	}
	else 
	{
		p->left = a;
	}	
}
struct TreeNode* insert(struct TreeNode* r,int num)
{
	/*struct TreeNode* a = (struct TreeNode*)malloc(sizeof(struct TreeNode));
	int num;
	scanf("%d",&num);
	a->data = num;
	a->left = NULL;
	a->right = NULL;*/
	if(r==NULL)
	{
		struct TreeNode* a = (struct TreeNode*)malloc(sizeof(struct TreeNode));
        	a->data = num;
        	a->left = NULL;
        	a->right = NULL;
		return a;
	}
	else
	{
		if(num >= r->data)
		{
			r->right = insert(r->right,num);
		} 
		else
		{
			r->left = insert(r->left,num);
		}
	return r;
	}

}

void preOrderSearch(struct TreeNode* r)
{
	if(r==NULL)
		return ;
	else 
	{
		preOrderSearch(r->left);
		printf("%d ",r->data);
		preOrderSearch(r->right);
	}
}