nyoj 221 Tree

#include<stdio.h>#include<string.h>#include<stdlib.h>typedef struct node{char data;struct node *lchild, *rchild; }Tree, *BiTree;                                   //&T代表指针 void tree(char *pre, char *in, BiTree &T, int l){//先序排列，中序排列，当前序列的长度 if(!l){    T = NULL;       return;}char ch = pre[0]; //得到根结点 int index = 0;while(in[index] != ch) index++;T = (BiTree)malloc(sizeof(Tree));//为根结点开辟空间 T->data = ch;//递归建立左子树和右子数tree(pre+1,in,T->lchild,index); //保证先序排列的第一个一直为根结点，                                //每确定一个根结点，先序排列就往后移一个 tree(pre+1+index, in+index+1, T->rchild, l-index-1); //用当前的先序排列加上//左子树根结点的位置加一就是右子数当前先序排列的顺序，第一个字母为右子数的根结点//中序排列的位置类似 }void Last(BiTree T){if(T){Last(T->lchild);Last(T->rchild);putchar(T->data);}} int main(){char pre[30], in[30];while(scanf("%s %s", pre, in) != EOF){int len = strlen(in);BiTree T; //T为BiTree类型的指针，指向根结点 tree(pre, in, T, len);Last(T);puts("");}return 0;}

Tree

时间限制：1000 ms  |  内存限制：65535 KB

难度：3

描述

Little Valentine liked playing with binary trees very much. Her favorite game was constructing randomly looking binary trees with capital letters in the nodes. 
This is an example of one of her creations: 

                                                D                                              / \                                             /   \                                            B     E                                           / \     \                                          /   \     \                                         A     C     G                                                    /                                                   /                                                  F

To record her trees for future generations, she wrote down two strings for each tree: a preorder traversal (root, left subtree, right subtree) and an inorder traversal (left subtree, root, right subtree). For the tree drawn above the preorder traversal is DBACEGF and the inorder traversal is ABCDEFG. 
She thought that such a pair of strings would give enough information to reconstruct the tree later (but she never tried it). 

Now, years later, looking again at the strings, she realized that reconstructing the trees was indeed possible, but only because she never had used the same letter twice in the same tree. 
However, doing the reconstruction by hand, soon turned out to be tedious. 
So now she asks you to write a program that does the job for her! 

输入

The input will contain one or more test cases.
Each test case consists of one line containing two strings preord and inord, representing the preorder traversal and inorder traversal of a binary tree. Both strings consist of unique capital letters. (Thus they are not longer than 26 characters.)
Input is terminated by end of file.

输出

For each test case, recover Valentine's binary tree and print one line containing the tree's postorder traversal (left subtree, right subtree, root).

样例输入

DBACEGF ABCDEFGBCAD CBAD

样例输出

ACBFGEDCDAB