레벨 순회 프로그램

#include<stdio.h>

#include<stdlib.h>

#define MAX_QUEUE_SIZE 100

typedef struct TreeNode{

int data;

struct TreeNode *left, *right;

}TreeNode;

typedef TreeNode *element;

typedef struct{

element queue[MAX_QUEUE_SIZE];

int front, rear;

}QueueType;

TreeNode n1={1 , NULL, NULL};

TreeNode n2={4 , &n1, NULL};

TreeNode n3={16 , NULL, NULL};

TreeNode n4={25 , NULL, NULL};

TreeNode n5={20 , &n3, &n4};

TreeNode n6={15 , &n2, &n5};

TreeNode *root=&n6;

void error(char *message){

fprintf(stderr,"%s\n",message);

exit(1);

}

void init(QueueType *q){

q->front = q->rear = 0;

}

int is_empty(QueueType *q){

return (q->front == q->rear);

}

int is_full(QueueType *q){

return ((q->rear+1)%MAX_QUEUE_SIZE == q-> front);

}

void enqueue(QueueType *q,element item){

if( is_full(q))

error("Q is fUll");

q->rear = (q->rear + 1) % MAX_QUEUE_SIZE;

q->queue[q->rear] = item;

}

element dequeue(QueueType *q){

if (is_empty(q))

error("Q is empty");

q->front = (q->front+1) % MAX_QUEUE_SIZE;

return q->queue[q->front];

}

void display_everything(QueueType *q){

int i,len;

len = (q->front)-(q->rear);

i=(q->front)+1;

while(i<MAX_QUEUE_SIZE){

printf("%c\n", q->queue[i]);

i++;

}

i=0;

while(i<len){

printf("%c\n", q->queue[i]);

i++;

}

}

void level_order(TreeNode *ptr){

QueueType q;

init(&q);

if(ptr == NULL) return;

enqueue(&q, ptr);

while(!is_empty(&q)) {

ptr = dequeue(&q);

printf("%d ", ptr->data);

if( ptr->left)

enqueue(&q, ptr->left);

if(ptr->right)

enqueue(&q, ptr->right);

}

}

int main(void){

level_order(root);

return 0;

}