#include <stdio.h>
#include <stdlib.h>
typedef struct BitNode{
char data;
struct BitNode *lchild,*rchild;
}BitTree;
BitTree *CreateBitTree (BitTree *&T)
{
char ch;
scanf ("%c",&ch);
if (ch == ' ') T = NULL;
else{
if (!(T = (BitTree * )malloc(sizeof(BitTree)))) printf("Error\n");
T ->data = ch;
CreateBitTree (T ->lchild);
CreateBitTree (T ->rchild);
}
return T;
}
void preorder(BitTree *T)
{
if(T!=NULL)
{
printf("%c",T->data);
if(T->lchild!=NULL||T->rchild!=NULL)
{
printf("(");
preorder(T->lchild);
if(T->rchild!=NULL) printf(",");
preorder(T->rchild);
printf(")");
}
}
}
BitTree *exchage(BitTree *&T)
{
BitTree *p;
if (T!=NULL)
{
p = T ->lchild;
T ->lchild = T ->rchild;
T ->rchild = p;
exchage(T ->lchild);
exchage(T ->rchild);
}
return T;
}
void main()
{
BitTree *root=NULL;
printf("input the tree\n");
root = CreateBitTree(root);
preorder(root);
root = exchage (root);
printf("\n");
preorder(root);
}
