HEU 1046 Tree Recovery

 1/**//**************************************
 2Problem: HEU 1046 Tree Recovery
 3Time: 0.0010 s
 4Memory: 240 k 
 5Accepted Time: 2009-03-25 14:37:24
 6Tips: 已知二叉树的先，中序，求后序。 
 7**************************************/
 8#include <stdio.h>
 9#include <string.h>
struct Node
{
    char c;
    Node *left;
    Node *right;
}tree[30];
char a[30],b[30];
int count1,count2,len;
void postord(Node *ptr)
{
    if(ptr!=NULL)
    {
        postord(ptr->left);
        postord(ptr->right);
        printf("%c",ptr->c);
    }
}
void fun(Node *ptr,int start,int end,int sign)
{
    for(int i=start;i<=end;i++)
    {
        if(a[count1]==b[i])
        {
            count1++;
            count2++;
            int temp=count2;
            tree[count2].c=b[i];
            if(ptr!=NULL)
            {
                if(sign==1)ptr->left=&tree[temp];
                else ptr->right=&tree[temp];
            }
            fun(&tree[temp],start,i-1,1);
            fun(&tree[temp],i+1,end,-1);
            break;
        }
    }
}

int main()
{
    while(scanf("%s%s",a,b)!=EOF)
    {
        len=strlen(a);
        count1=0;
        count2=-1;
        for(int i=0;i<len;i++)tree[i].left=tree[i].right=NULL;
        fun(NULL,0,len-1,1);
        postord(&tree[0]);
        printf("\n");
    }
    return 0;
}