pat1064. Complete Binary Search Tree (30)

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:

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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提交代码

 

#include<cstdio>
#include<stack>
#include<algorithm>
#include<iostream>
#include<stack>
#include<set>
#include<map>
#include<cmath>
using namespace std;
int line[1005],tree[1005];
void Build(int *line,int *tree,int n,int cur){
    if(!n){
        return;
    }
    int h=log(n)/log(2);
    int x=n-(pow(2,h)-1);

    //cout<<"x: "<<x<<endl;

    if(x>pow(2,h-1)){
       x=pow(2,h-1);
    }

    //cout<<"x: "<<x<<endl;

    int l=pow(2,h-1)+x-1;

    //cout<<"l:  "<<l<<endl;

    tree[cur]=line[l];
    Build(line,tree,l,cur*2+1);
    Build(line+l+1,tree,n-l-1,cur*2+2);
}
int main(){
    //freopen("D:\\INPUT.txt","r",stdin);
    int n,i;
    scanf("%d",&n);
    for(i=0;i<n;i++){
        scanf("%d",&line[i]);
    }
    sort(line,line+n);
    Build(line,tree,n,0);
    printf("%d",tree[0]);
    for(i=1;i<n;i++){
        printf(" %d",tree[i]);
    }
    printf("\n");
    return 0;
}