ZCMU-4932 tree search (water, complete binary tree search)

Water problem, just review the binary tree, and then explore the law of the binary tree

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Question stem

4932: Tree lookup

Time Limit: 1 Sec Memory Limit: 32 MB
Submit: 46 Solved: 28
[Submit][Status][Web Board]
Description

There is a tree that outputs all nodes of a certain depth, if there is a tree, these nodes are output, and if there is no tree, EMPTY is output. The tree is a complete binary tree.

Input

There are multiple sets of data entered.
Enter one n for each group (1<=n<=1000), then enter the n nodes in the tree in turn, and enter a d for depth.

Output

Output all nodes in the d-th level of the tree, separated by spaces, and there is no space after the last node.

Sample Input

5
1 2 3 4 5 
7
7
1 2 3 4 5 6 7 
2
0

Sample Output

EMPTY
2 3

idea

This question is actually the law of the
binary tree. The law of the binary tree is that the first branch of the nth layer is pow(2, n-1), and the nth layer has pow(2, n-1) nodes, then the idea of ​​this question is very simple , Open directly

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AC code

#include<bits/stdc++.h>
using namespace std;
const int maxn = 1e3+10;
typedef long long ll;
int a[maxn];
int main()
{
    
    
    int n,d;
    while(cin>>n&&n)
    {
    
    
        memset(a, 0, sizeof a);
        for(int i=1;i<=n;i++)cin >> a[i];
        cin >> d;
        int start = pow(2,d-1);
        if(start>n)puts("EMPTY");
        else{
    
    
            int len = 2*start - 1;
            //题目说了这是一个完全二叉树，所以下一行可以省去
            if(len>n)len = n;
            for(int i=start;i<=len;i++){
    
    
                if(i!=start)printf(" ");
                printf("%d",a[i]);
            }
            puts("");
        }
    }
    return 0;
}

to sum up

Water problem