HDU（3999）The order of a Tree

As we know,the shape of a binary search tree is greatly related to the order of keys we insert. To be precisely:
1.  insert a key k to a empty tree, then the tree become a tree with
only one node;
2.  insert a key k to a nonempty tree, if k is less than the root ,insert
it to the left sub-tree;else insert k to the right sub-tree.
We call the order of keys we insert “the order of a tree”,your task is,given a oder of a tree, find the order of a tree with the least lexicographic order that generate the same tree.Two trees are the same if and only if they have the same shape.

 

 

Input

There are multiple test cases in an input file. The first line of each testcase is an integer n(n <= 100,000),represent the number of nodes.The second line has n intergers,k1 to kn,represent the order of a tree.To make if more simple, k1 to kn is a sequence of 1 to n.

 

 

Output

One line with n intergers, which are the order of a tree that generate the same tree with the least lexicographic.

 

 

Sample Input

4 1 3 4 2

 

 

Sample Output

1 3 2 4

Source

2011 Multi-University Training Contest 16 - Host by TJU

简单的二叉树题目，先建树，再前序遍历（开始以为中序呢，囧！）。

#include <stdio.h>
#include <string.h>
#include <stdlib.h>
typedef struct node
{
    int n;
    struct node *l,*r;
}BT;
BT* ct(BT *p,int n)//建树
{
    if(p==NULL)
      {
         p=(BT*)malloc(sizeof(BT));
         p->n=n;
         p->l=p->r=NULL;
         return p;
      }
     if(p->n>n)
        p->l=ct(p->l,n);
       else
        p->r=ct(p->r,n);
    return p;
}
void ds(BT *p,int c)//前序遍历
{
    if(c!=1)
       printf(" %d",p->n);
     else
       printf("%d",p->n);
     if(p->l!=NULL)
      ds(p->l,2);
    if(p->r!=NULL)
       ds(p->r,2);
}
int main()
{
   int i,n,m;
  BT *p=NULL;
  while(scanf("%d",&n)!=EOF)
  {
       for(i=0;i<n;i++)
        {
            scanf("%d",&m);p=ct(p,m);
        }
      ds(p,1);printf("\n");
  }

  return 0;
}
                                                                                     ------江财小子