(p138)只用固定量额外存储空间不用递归遍历二叉树

来源：互联网发布：sql查询分析执行编辑：程序博客网时间：2024/06/06 11:39

我写过最搞笑的程序：基本思路就是记录从哪个方向到达节点，很多都是复制粘贴^-^

/* * source.c * *  Created on: Feb 25, 2016 *      Author: wing *//* * source.c * *  Created on: Feb 25, 2016 *      Author: wing */#include<stdio.h>#include<stdlib.h>#define maxsize 1000struct node{char n;struct node *p,*l,*r;};struct stack{struct node **head;int top;};int build(struct node **parent)/*递归建立二叉树*/{char n;scanf("%c",&n);if (n=='#'){*parent=NULL;return 0;}else{*parent=(struct node *)malloc(sizeof(struct node));(*parent)->n=n;build(&(*parent)->l);if ((*parent)->l!=NULL)(*parent)->l->p=*parent;build(&(*parent)->r);if ((*parent)->r!=NULL)(*parent)->r->p=*parent;return 0;}}int initstack(struct stack *st){st->head=(struct node**)malloc(sizeof(struct node*)*(maxsize));st->top=-1;return 0;}int push(struct stack *st,struct node *next){st->head[++(st->top)]=next;return 0;}struct node *pop(struct stack *st){return st->head[st->top--];}int pretrav(struct node *root){struct node *next=root;int dir=1;while (next!=NULL){if(dir==1){printf("%c",next->n);if (next->l!=NULL){next=next->l;dir=1;}elseif (next->r!=NULL){next=next->r;dir=1;}else{if (next->p==NULL){next==NULL;break;}if (next==next->p->l)dir=2;elsedir=3;next=next->p;}}if (dir==2)if (next->r!=NULL){next=next->r;dir=1;}else{if (next->p==NULL){next=NULL;break;}if (next==next->p->l)dir=2;elsedir=3;next=next->p;}if (dir==3){if (next->p==NULL){next=NULL;break;}if (next==next->p->l)dir=2;elsedir=3;next=next->p;}}return 0;}int main(void){struct node **root;root=(struct node **)malloc(sizeof(struct node*));build(root);printf("先序遍历：");pretrav(*root);return 0;}

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