[PAT] A1064

link:https://www.patest.cn/contests/pat-a-practise/1064

1064. Complete Binary Search Tree (30)

时间限制

100 ms

内存限制

65536 kB

代码长度限制

16000 B

判题程序

Standard

作者

CHEN, Yue

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:

101 2 3 4 5 6 7 8 9 0

Sample Output:

6 3 8 1 5 7 9 0 2 4

AC:

#include <iostream>#include <algorithm>using namespace std;int num[1010] = {0}, index = 0, n, tree[1010];void inOrder(int root){    if(root > n) return;    inOrder(root * 2);    tree[root] = num[index++];    inOrder(root * 2 + 1);}int main(){    cin >> n;    for(int i = 0; i < n; i++){        cin >> num[i];    }    sort(num, num + n);    inOrder(1);    for(int i = 1; i <=n; i++){        cout << tree[i];        if(i < n) cout << " ";    }    cout << endl;    return 0;}