(p138)非递归完成二叉树的遍历

来源：互联网发布：如何在淘宝上交水电费编辑：程序博客网时间：2024/06/07 03:24

花了将近一个星期才搞懂了非递归遍历的方式，其中后序遍历真心麻烦，具体参考百度百科后序遍历和http://blog.csdn.net/cqnuztq/article/details/8896953

/* * source.c * *  Created on: Feb 25, 2016 *      Author: wing */#include<stdio.h>#include<stdlib.h>#define maxsize 1000struct node{char n;struct node *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);build(&(*parent)->r);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;struct stack st;initstack(&st);next=root;while (next!=NULL||st.top>=0){if (next!=NULL){printf("%c ",next->n);push(&st,next);next=next->l;}else{next=pop(&st);next=next->r;}}free(st.head);return 0;}int intrav(struct node *root){struct stack st;struct node *next;initstack(&st);next=root;while (next!=NULL||st.top>=0){if (next!=NULL){push(&st,next);next=next->l;}else{next=pop(&st);printf("%c ",next->n);next=next->r;}}free(st.head);return 0;}int postrav(struct node *root){struct node *next,*prev;struct stack st;initstack(&st);next=root;while (next!=NULL||st.top>=0){while(next!=NULL){push(&st,next);next=next->l;}prev=NULL;while (st.top>=0){next=st.head[st.top];if (next->r==prev){printf("%c ",next->n);prev=pop(&st);}else{next=next->r;break;}}if (st.top==-1)break;}return 0;}int main(void){struct node **root;root=(struct node **)malloc(sizeof(struct node*));build(root);printf("先序遍历：");pretrav(*root);printf("\n中序遍历：");intrav(*root);printf("\n后序遍历：");postrav(*root);return 0;}

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