輸入用例：

BAC

BCA

XDEFAG

XEDGAF

輸出用例：

ABC

FDXEAG

思路與前面那道由前序中序輸出後序思路一樣，前面有詳細的解答

 ///
 /// @file    test.cc
 /// @author  miaobeihai([email protected])
 /// @date    2017-03-05 16:31:36
 ///
#include<stdio.h>
#include<string.h>
int loc=0;
char str1[100],str2[100];
struct Node{
	Node *rchild;
	Node *lchild;
	int data;
}Tree[50];
Node *create()
{
	Tree[loc].rchild=Tree[loc].lchild=NULL;
	return &Tree[loc++];
}

void preOrder(Node *T)
{
	if(T){
		printf("%c",T->data);
		if(T->lchild!=NULL)
	    	preOrder(T->lchild);
		if(T->rchild!=NULL)
			preOrder(T->rchild);
		//printf("%c",T->data);
	}
}
Node *build(int s1,int e1,int s2,int e2)
{
	int idx,i;
	Node *T=create();
	T->data=str2[e2];
	for(i=s1;i<=e1;i++)
	{
		if(str1[i]==str2[e2]){
			idx=i;
			break;
		}
	}
	if(idx!=s1)
	{
		T->lchild=build(s1,idx-1,s2,s2+(idx-s1-1));
	}
	if(idx!=e1)
	{
		T->rchild=build(idx+1,e1,s2+(idx-s1),e2-1);
	}
	return T;
}
int main()
{
	while(scanf("%s",str1)!=EOF)
	{
		scanf("%s",str2);
		int len1=strlen(str1);
		int len2=strlen(str2);
	    Node *T=build(0,len1-1,0,len2-1);
		preOrder(T);
		printf("\n");
	}
	return 0;
}