打印二叉树

首先根据前序和中序构造一棵二叉树，然后利用中序遍历和广度优先将树按照形状打印出来。

#include <stdio.h>

#include <string.h>

#include <stdlib.h>

#define MAX 1000

/*

print the tree

first:using the preorder and inoder,create a tree

then print it using bst and preorder

*/

int i=1; //标记中序中的顺序

//队列的简单实现

struct node * queue[MAX];//队列 ,未考虑溢出

int head = 0;

int tail = 0;

struct node * dequeue(){

    struct node * temp = queue[head];

    head++;

    head %= MAX;

    return temp;



}

void enqueue(struct node * n){

    queue[tail] = n;

    tail++;

    tail %= MAX;

}

int isempty(){

    return (head == tail);

}



//树的实现

struct node {

    int key;

    int level; //表示该节点打印出来后距离最左侧的距离

    struct node * left;

    struct node * right;

}*root;

struct node * newNode(){

    struct node * temp= (struct node *)malloc(sizeof(struct node));

    memset(temp,0,sizeof(*temp));

    return temp;

}

//根据前序及中序序列，构造树，size表示树中总节点数

struct node * creatTree(char * inorder,char * preorder,int size){

    char * pos = inorder;

    struct node * root = newNode();

    int leftsize;

    if(size < 1){

        return NULL;

    }

    root -> key = *preorder;

    while(*pos != '\0' && *pos != *preorder)

        pos++;

    leftsize = pos - inorder;

    root -> left = creatTree(inorder,preorder+1,leftsize);

    root -> right = creatTree(pos+1,preorder+leftsize+1,size-1-leftsize);

    return root;

}

//中序遍历，并将节点level计算

void inOrder(struct node * root){

    if(root == NULL)

        return ;

    inOrder(root -> left);

    root -> level = i;

    i++;

    printf("%d ",root -> level);

    inOrder(root -> right);



}

//bfs

void bfs(struct node * root){

    struct node * last;

    struct node * curr;

    struct node * prev;

    int distance = 0;//上一个节点距离最左侧的距离

    last = root;

    enqueue(root);

    while(!isempty()){

        curr = dequeue();

        printf("%*c",curr->level - distance,curr -> key);

        distance = curr -> level;

        if(curr -> left != NULL){

            prev = curr -> left;

            enqueue(prev);

        }

        if(curr -> right != NULL){

            prev = curr -> right;

            enqueue(prev);

        }

        if(curr == last){

            printf("\n");

            last = prev;

            distance = 0;

        }



    }

}



int main(){

    char * inorder="123456";

    char * preorder="321456";

    root = creatTree(inorder,preorder,6);

    printf("inOrder:\n");

    inOrder(root);

    printf("\nBFS:\n");

    bfs(root);

    return 0;



}转载自：http://duanple.blog.163.com/blog/static/70971767200822411729791/