面试题 19

1 题目描述

2 算法描述

3 C 语言实现

#include<stdio.h>

// Tree
typedef int ElemType;
typedef struct node{
ElemType data;
struct node *lchild,*rchild;
}TNode,*Tree;

// Stack node1即为栈元素SNode也为队元素QNode
typedef struct node1{
TNode* data;
struct node1 *next;
}SNode,QNode,*Stack;

//初始化头结点
void initStack(Stack* stack){
(*stack)=(SNode*)malloc(sizeof(SNode));
(*stack)->data=NULL;
(*stack)->next=NULL;
}
//所有操作都在表头进行,头插法
int push(Stack stack,TNode* data){
SNode *push;
//如果Stack尚未初始化
if(stack==NULL) return 0;
push=(SNode*)malloc(sizeof(SNode));
push->data=data;
push->next=stack->next;
stack->next=push;
}
//出栈
int pop(Stack stack,TNode** popVlaue){
//如果Stack为空
if(isEmpty(stack)) return 0;
SNode *pop=stack->next;
*popVlaue=pop->data;
stack->next=pop->next;
free(pop);
return 1;
}
//获得栈顶元素
int getTop(Stack stack,TNode** topVlaue){
//如果Stack为空
if(isEmpty(stack)) return 0;
*topVlaue=stack->next->data;
return 1;
}
//判断是否为空
int isEmpty(Stack stack){
return stack!=NULL&&stack->next==NULL?1:0;
}
//创建二叉树
TNode* createTree(){
ElemType data;
scanf("%d",&data);
TNode* node;
if(data==0) return NULL;
node=(TNode*)malloc(sizeof(TNode));
node->data=data;
node->lchild=createTree();
node->rchild=createTree();
return node;
}
//先序遍历
void preOrder(TNode* node){
if(node==NULL) return;
printf("%d",node->data);
preOrder(node->lchild);
preOrder(node->rchild);
}

//非递归先序遍历
void _preOrder(Tree tree){
Stack stack;
initStack(&stack);
TNode *p=tree;
while(p!=NULL||!isEmpty(stack)){
if(p!=NULL){
printf("%d",p->data);
push(stack,p);
p=p->lchild;
}else{
pop(stack,&p);
p=p->rchild;
}
}
}
void mirroTree(TNode* node){
TNode* temp;
if(node==NULL) return;
if(node->lchild==NULL&&node->rchild==NULL){
return;
}
temp=node->lchild;
node->lchild=node->rchild;
node->rchild=temp;
mirroTree(node->lchild);
mirroTree(node->rchild);
}

void mirroTree_1(TNode* tree){
Stack stack;
initStack(&stack);
TNode *p=tree;
TNode* temp;
while(p!=NULL||!isEmpty(stack)){
if(p!=NULL){
if(!(p->lchild==NULL&&p->rchild==NULL)){
temp=p->lchild;
p->lchild=p->rchild;
p->rchild=temp;
}
push(stack,p);
p=p->lchild;
}else{
pop(stack,&p);
p=p->rchild;
}
}
}

void main(){
Tree tree;
tree=NULL;
printf("%s:","请输入二叉树的元素");
tree=createTree();
printf("\n%s:","先序递归遍历原始二叉树结果");
preOrder(tree);

printf("\n%s:","先序递归遍历镜像二叉树结果");
mirroTree(tree);
preOrder(tree);

printf("\n%s:","先序递归遍历镜像二叉树镜像结果");
mirroTree_1(tree);
preOrder(tree);
}