二叉树层次遍历的应用--改造二叉链表

一 问题描述

二 解题思路

    利用二叉树的层次遍历，识别出不同层次，当某一层中的结点未从队列中出完时，那么刚出队列的结点的右相邻结点就是对头元素。

三 测试效果

四 代码

/* * to transform a binary tree*/#include <stdio.h>#include <stdlib.h>#include <math.h>#define ElemType int#define END -1#define MAX 100typedef struct BinNode {ElemType data;struct BinNode *left;struct BinNode *right;struct BinNode *sibling;}BinNode;typedef struct QueueNode {struct BinNode *data;struct QueueNode *next;}QueueNode;QueueNode *front, *rear;void InQueue(struct BinNode *e) {QueueNode *p = (QueueNode *)malloc(sizeof(QueueNode));if(!p) {perror("memory error!\n");exit(EXIT_FAILURE);}p->data = e;p->next = 0;        if(rear) rear->next = p;rear = p;if(!front) front = rear;}struct BinNode *DeQueue() {if(!front) {perror("the queue is empty!\n");exit(EXIT_FAILURE);}struct BinNOde *p = front->data;QueueNode *r = front;front = front->next;free(r);if(!front) rear = NULL;return p;}int QueueEmpty() {return  front == NULL?1:0;}struct BinNode *front_of_queue() {return front->data;}void CreateBinTree(BinNode **t) {ElemType e;if(scanf("%d", &e) != 1) {perror("input error!\n");exit(EXIT_FAILURE);}if(e == END) return;if(*t == NULL) {*t = (BinNode *)malloc(sizeof(BinNode));if(*t == NULL) {perror("memory error!\n");exit(EXIT_FAILURE);}(*t)->left = NULL;(*t)->right = NULL;(*t)->sibling = NULL;(*t)->data = e;}CreateBinTree(&((*t)->left));CreateBinTree(&((*t)->right));}void PreTranverse(BinNode *t) {if(t) {printf("%d\t", t->data);if(t->sibling) {printf("--%d\t", t->sibling->data);}PreTranverse(t->left);PreTranverse(t->right);}}void TransformBinTree(BinNode **t) {if(!(*t)) return;int level = 1;   // the level of bintreeint thislevel;   // the number of nodes in this levelint nextlevel;   // the number of nodes in next levelint k = 0;       // the number of leaves in bintree int i, j;BinNode *p;        InQueue(*t);thislevel = 1;  // when the root node is added into the queuenextlevel = 0;        while(!QueueEmpty()) {p = DeQueue();thislevel--;  // when a node is out from the queueif(p->left) {InQueue(p->left);nextlevel++;  // the children of current node}if(p->right) {InQueue(p->right);nextlevel++;}if(!thislevel) {thislevel = nextlevel;nextlevel = 0;level++;}else p->sibling = front_of_queue();}}int main() {BinNode *root = NULL;CreateBinTree(&root);PreTranverse(root);printf("\n");        TransformBinTree(&root);PreTranverse(root);        printf("\n");return 0;}

五 编程体会

   关键是运用队列和搞清层次遍历的时候每一层结点的情况。