PAT 1064 Complete Binary Search Tree（30 分）(完全二叉排序树)

A Binary Search Tree (BST) is recursively defined as a binary tree which has the following properties:

• The left subtree of a node contains only nodes with keys less than the node's key.
• The right subtree of a node contains only nodes with keys greater than or equal to the node's key.
• Both the left and right subtrees must also be binary search trees.

A Complete Binary Tree (CBT) is a tree that is completely filled, with the possible exception of the bottom level, which is filled from left to right.

Now given a sequence of distinct non-negative integer keys, a unique BST can be constructed if it is required that the tree must also be a CBT. You are supposed to output the level order traversal sequence of this BST.

Input Specification:

Each input file contains one test case. For each case, the first line contains a positive integer N (≤1000). Then N distinct non-negative integer keys are given in the next line. All the numbers in a line are separated by a space and are no greater than 2000.

Output Specification:

For each test case, print in one line the level order traversal sequence of the corresponding complete binary search tree. All the numbers in a line must be separated by a space, and there must be no extra space at the end of the line.

Sample Input:

10
1 2 3 4 5 6 7 8 9 0

Sample Output:

6 3 8 1 5 7 9 0 2 4

题解：题意是给出n个整数，用这几个整数构建完全二叉排序树，输出这棵完全二叉排序树的层次遍历。

代码：

#include<bits/stdc++.h>
using namespace std;
const int maxn=1010;
int n=0,number[maxn],CBT[maxn],k;
void inOrder(int root)
{                               //注意
    if(root>n)
        return;                 //void 对应 return  int对应return 0
    inOrder(2*root);
    CBT[root]=number[k++];
    inOrder(2*root+1);
}
int main()
{
    scanf("%d",&n);
    for(int i=0;i<n;i++)
        scanf("%d",&number[i]);
    sort(number,number+n);
    inOrder(1);
    for(int i=1;i<=n;i++)
    {
        printf("%d",CBT[i]);
        if(i<n)
            printf(" ");
    }
    return 0;
}