#include <iostream>
#include <cstdlib>
#include <string.h>
#include <algorithm>
#define ss(a)  scanf("%d",&a)
#define ss64(a)  scanf("%I64d",&a)
using namespace std;

typedef struct Node
{
    struct Node *l;
	struct Node *r;
	int num;
}*node;

void creat(node &T,int num)             //此处的&的引用是关键
{
   if (T == NULL)
   {
       T = (node)malloc(sizeof(Node));
	   T->num = num;
	   T->l = NULL;
	   T->r = NULL;;
   }
   else
	   if (num < T->num)
	   {
		   creat(T->l,num);
	   }
	   else
	   {
		   creat(T->r,num);
	   }

}

void post_visit(node T,int x)
{
    if (T != NULL)
    {
		if(x)
		   cout<<T->num;
		else
		   cout<<" "<<T->num;
		post_visit(T->l,0);
		post_visit(T->r,0);
    }
}

int main()
{
	int i,n,m,sum,cnt,j;
	int num;
	node T=NULL;
	while(~ss(n))
	{
		for (i=0;i<n;i++)
        {
			 ss(num);
			 creat(T,num);
		}
        post_visit(T,1);
		cout<<endl;
	}
    return 0;
}

考察二叉树的创建以及先序遍历

The order of a Tree

Time Limit: 2000/1000 MS (Java/Others)    Memory Limit: 32768/32768 K (Java/Others)

Problem Description

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