1064. Complete Binary Search Tree (30)

柔光的暖阳◎ 2022-05-29 23:39 130阅读 0赞

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

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题目大意：

代码：

#include<stdio.h>
    #include<algorithm>
    using namespace std;
    int arr[1010],level[1010],n,num=0;
    void DFS(int root)
    {
        if(root<n)
        {
            DFS(root*2+1);
            level[root]=arr[num++];
            DFS(root*2+2);
        }
    }
    int main()
    {
        int i,j,m,k,t;
        scanf("%d",&n);
        for(i=0;i<n;i++)
        {
            scanf("%d",&arr[i]);
        }
        sort(arr,arr+n);
        DFS(0);
        for(i=0;i<n;i++)
        {
            if(i==0)
                printf("%d",level[i]);
            else
                printf(" %d",level[i]);
        }
        return 0;
    }