题目1521：二叉树的镜像

题目描述：
输入一个二叉树，输出其镜像。




输入：
输入可能包含多个测试样例，输入以EOF结束。

对于每个测试案例，输入的第一行为一个整数n(0<=n<=1000,n代表将要输入的二叉树节点的个数（节点从1开始编号）。接下来一行有n个数字,代表第i个二叉树节点的元素的值。接下来有n行，每行有一个字母Ci。

Ci=’d’表示第i个节点有两子孩子，紧接着是左孩子编号和右孩子编号。

Ci=’l’表示第i个节点有一个左孩子，紧接着是左孩子的编号。

Ci=’r’表示第i个节点有一个右孩子，紧接着是右孩子的编号。

Ci=’z’表示第i个节点没有子孩子。

输出：
对应每个测试案例，

按照前序输出其孩子节点的元素值。

若为空输出NULL。
代码一：在构建树的过程中直接对左右孩子进行交换。

#include<stdio.h>
#include<stdlib.h>

typedef struct tree
{
int data;
struct tree *left;
struct tree *right;
}Node;
Node *Atree[1099];

void create(Node *node[],int a[], int n)
{
char type;
int left,right;
for(int i = 1; i <= n; i++)
{
node[i]->data = a[i];
scanf("\n%c",&type);
if(type == 'd')
{
scanf("%d %d",&left,&right);
node[i]->right = node[left];
node[i]->left = node[right];
}
else if(type == 'l')
{
scanf("%d",&left);
node[i]->right = node[left];
node[i]->left = NULL;
}
else if(type == 'r')
{
scanf("%d",&right);
node[i]->right = NULL;
node[i]->left = node[right];
}
else if(type == 'z')
{
node[i]->left = NULL;
node[i]->right = NULL;
}
}
}

//前序打印树
int flag = 0;
void print(Node *tree)
{
if(tree != NULL)
{
if(flag == 0)
{
printf("%d",tree->data);
flag = 1;
}
else
printf(" %d",tree->data);
print(tree->left);
print(tree->right);
}
}
int main()
{
int n;
while(scanf("%d",&n) != EOF)
{
if( n <= 0)
{
printf("NULL\n");
}
else
{
int a[n + 1];
for(int i = 1; i <= n; i++)
Atree[i] = new Node;
for(int i = 1; i <= n; i++)
scanf("%d",&a[i]);
create(Atree,a,n);
print(Atree[1]);
printf("\n");
//清空
for(int i = 1;i <= n;i++)
{
delete Atree[i];
Atree[i]=NULL;
}
}
}
}

 

代码二：构建树后按照父节点->右孩子->左孩子的顺序打印

#include<stdio.h>
#include<stdlib.h>

typedef struct tree
{
int data;
struct tree *left;
struct tree *right;
}Node;
Node *Atree[1099];

void create(Node *node[],int a[], int n)
{
char type;
int left,right;
for(int i = 1; i <= n; i++)
{
node[i]->data = a[i];
scanf("\n%c",&type);
if(type == 'd')
{
scanf("%d %d",&left,&right);
node[i]->left = node[left];
node[i]->right = node[right];
}
else if(type == 'l')
{
scanf("%d",&left);
node[i]->left = node[left];
node[i]->right = NULL;
}
else if(type == 'r')
{
scanf("%d",&right);
node[i]->left = NULL;
node[i]->right = node[right];
}
else if(type == 'z')
{
node[i]->left = NULL;
node[i]->right = NULL;
}
}
}

//按父节点->右孩子->左孩子的顺序打印
int flag = 0;
void print(Node *tree)
{
if(tree != NULL)
{
if(flag == 0)
{
printf("%d",tree->data);
flag = 1;
}
else
printf(" %d",tree->data);
print(tree->right);
print(tree->left);
}
}

int main()
{
int n;
while(scanf("%d",&n) != EOF)
{
if( n <= 0)
{
printf("NULL\n");
}
else
{
int a[n + 1];
for(int i = 1; i <= n; i++)
Atree[i] = new Node;
for(int i = 1; i <= n; i++)
scanf("%d",&a[i]);
create(Atree,a,n);
print(Atree[1]);
printf("\n");
//清空
for(int i = 1;i <= n;i++)
{
delete Atree[i];
Atree[i]=NULL;
}
}
}
}

代码三：构建树后递归交换树的左右子节点，最后前序打印。

#include<stdio.h>
#include<stdlib.h>

typedef struct tree
{
int data;
struct tree *left;
struct tree *right;
}Node;
Node *Atree[1099];

void create(Node *node[],int a[], int n)
{
char type;
int left,right;
for(int i = 1; i <= n; i++)
{
node[i]->data = a[i];
scanf("\n%c",&type);
if(type == 'd')
{
scanf("%d %d",&left,&right);
node[i]->left = node[left];
node[i]->right = node[right];
}
else if(type == 'l')
{
scanf("%d",&left);
node[i]->left = node[left];
node[i]->right = NULL;
}
else if(type == 'r')
{
scanf("%d",&right);
node[i]->left = NULL;
node[i]->right = node[right];
}
else if(type == 'z')
{
node[i]->left = NULL;
node[i]->right = NULL;
}
}
}

void mirrorTree(Node *tree)
{
if(tree == NULL || (tree->left == NULL && tree->right == NULL))
return;
Node *p = tree->left;
tree->left = tree->right;
tree->right = p;
mirrorTree(tree->left);
mirrorTree(tree->right);
}

//前序打印树
int flag = 0;
void print(Node *tree)
{
if(tree != NULL)
{
if(flag == 0)
{
printf("%d",tree->data);
flag = 1;
}
else
printf(" %d",tree->data);
print(tree->left);
print(tree->right);
}
}
int main()
{
int n;
while(scanf("%d",&n) != EOF)
{
if( n <= 0)
{
printf("NULL\n");
}
else
{
int a[n + 1];
for(int i = 1; i <= n; i++)
Atree[i] = new Node;
for(int i = 1; i <= n; i++)
scanf("%d",&a[i]);
create(Atree,a,n);
mirrorTree(Atree[1]);
print(Atree[1]);
printf("\n");
//清空
for(int i = 1;i <= n;i++)
{
delete Atree[i];
Atree[i]=NULL;
}
}
}
}