树6 Complete Binary Search Tree

题目：https://pintia.cn/problem-sets/1268384564738605056/problems/1276814005115539458

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

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

• 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.

题解：https://www.liuchuo.net/archives/2161
代码：

#include <iostream>
#include <algorithm>
using namespace std;
int in[1010], level[1010], n, t = 0;
void inOrder(int root) {
    if (root >= n) return ;
    inOrder(root * 2 + 1);
    level[root] = in[t++];
    inOrder(root * 2 + 2);
}
int main() {
    scanf("%d", &n);
    for (int i = 0; i < n; i++)
        scanf("%d", &in[i]);
    sort(in, in + n);
    inOrder(0);
    printf("%d", level[0]);
    for (int i = 1; i < n; i++)
        printf(" %d", level[i]);
    return 0;
}