# 04-树6 Complete Binary Search Tree（30 分）

xiaoxiao2021-02-28  5

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

#include <iostream> #include <algorithm> using namespace std; const int maxn=1001; int N; int input[maxn],tree[maxn],pos=0; void inputData() { cin>>N; for(int i=0;i<N;i++) { cin>>input[i]; } } void buildTree(int root) { int leftChild=2*root,rightChild=2*root+1; if(root>N) return; buildTree(leftChild); tree[root]=input[pos++]; buildTree(rightChild); } void output() { for(int i=1;i<=N;i++) { if(i!=N) cout<<tree[i]<<" "; else cout<<tree[i]; } } int main() { inputData(); sort(input,input+N); buildTree(1); output(); return 0; }