Falling Leaves

http://poj.org/problem?id=1577

#include <stdio.h>
#include <string.h>
#include <malloc.h>
typedef struct BiTree
{

    char ch;
    struct BiTree *lchild;
    struct BiTree *rchild;
}BiTree;


BiTree *createBiTree(char ch)
{
    BiTree *leaf = (BiTree *)malloc(sizeof(BiTree));
    leaf->ch = ch;
    leaf->lchild = NULL;
    leaf->rchild = NULL;
    return leaf;
}
BiTree *insertBiTree(BiTree *root, char ch)
{
    BiTree *leaf = root;

    if(root == NULL)
    {
        root = createBiTree(ch);
        return root;
    }

    while(leaf)
    {
        if((leaf->ch) > ch)
        {
            if(leaf->lchild == NULL)
            {
                leaf->lchild = createBiTree(ch);
                break;
            }
            else
            {
                leaf = leaf->lchild;
            }
        }
        else  if((leaf->ch) < ch)
        {
            if(leaf->rchild == NULL)
            {
                leaf->rchild = createBiTree(ch);
                break;
            }
            else
            {
                leaf = leaf->rchild;
            }
        }
    }

    return root;
}

void preorder(BiTree *root)
{
    if(root!=NULL)
    {
        printf("%c", root->ch) ;
        preorder(root->lchild) ;
        preorder(root->rchild) ;
    }

}

int main()
{
    char str[50], p[10000];
    int length;
    int i;
    BiTree *root = NULL;


    while(1)
    {
        scanf("%s", str);
        if(strcmp(str, "*") == 0 || strcmp(str, "$") == 0)
        {
            length = strlen(p);
            for(i = length-1; i >= 0; i--)
            {
               root = insertBiTree(root, p[i]);
            }
            preorder(root);
            printf("\n");
            if(strcmp(str, "$") == 0)  break;
            root = NULL;
            memset(p, '\0', sizeof(p));

        }
        else
        {
            strcat(p, str);
        }
    }

    return 0;
}

题目大意:按照题目给出的叶子顺序,找出原来的二叉排序树。

解：按照题目给出的顺序,倒过来插入到二叉排序树中即可构造原来的树。