Rebuilding a binary tree

Rebuilding a binary tree

Description

The question is very simple. I will give you a post-order and mid-order sequence of a binary tree and find its pre-order sequence (so easy !).

 

Input

The input contains multiple groups of data (less than 100 groups), ending with a file. Each group contains only one row of data, including two strings separated by spaces, indicating the post-order and Middle-order sequences of Binary Trees (the string length is less than 26, and the input data is valid ).

Output

Each group of output data occupies a single row. The output data must be sorted first.

Sample Input

ACBFGED ABCDEFGCDAB CBAD

Sample output

DBACEGFBCAD

  #include <iostream>#include <string.h>using namespace std;struct tree{    char data;    tree *left;    tree *right;};tree *converse(char *pos,char *in,int n,int m){    tree *b;    int k=0; char *p,*q,*maxp; int maxpost,maxin;    if(n<=0)    {        return NULL;            }    maxpost=-1;    for(p=in;p<in+n;p++)    for(q=pos;q<pos+m;q++)        if(*p==*q)        {            k=q-pos;            if(k>maxpost)            {                maxpost=k;                maxp=p;                maxin=p-in;            }        }            b=new tree;        b->data=pos[maxpost];        b->left=converse(pos,in,maxin,m);    b->right=converse(pos,maxp+1,n-maxin-1,m);    return b;}void pre(tree *b){    if(b)    {        cout<<b->data;        pre(b->left);                pre(b->right);    }}int main(){    char c1[1000],c2[1000];    while(cin>>c1>>c2)    {        tree *b;        b=converse(c1,c2,strlen(c1),strlen(c2));        pre(b);        cout<<endl;    }    return 0;}                 

 

Rebuilding a binary tree