浙大数据结构04-树6 Complete Binary Search Tree_完全二叉搜索树
作者:互联网
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
结尾无空行
Sample Output:
6 3 8 1 5 7 9 0 2 4
结尾无空行
链表:
#include <bits/stdc++.h>
#define x first
#define y second
using namespace std;
typedef long long ll;
int a[1024] = {0};
typedef struct node *BST;
struct node
{
int value;
BST left, right;
};
BST buildTree (int start, int n) // 从start开始的n个数字,找CBST的树根
{
if (n < 1)
{
return NULL;
}
int full = 1, botton_cnt = 1;
while (full < n)
{
botton_cnt *= 2;
full += botton_cnt;
}
int lack = full - n;
int left_cnt = (full - 1) / 2;
if (lack > botton_cnt / 2)
{
left_cnt -= lack - botton_cnt / 2;
}
// [start,start+n]
BST root = (BST) malloc (sizeof (struct node) );
root->value = a[start + left_cnt];
root->left = buildTree (start, left_cnt);
root->right = buildTree (start + left_cnt + 1, n - left_cnt - 1);
return root;
}
int main()
{
// system("chcp 65001");
std::ios::sync_with_stdio (false);
cin.tie (0);
cout.tie (0);
// freopen("C:/Users/zhaochen/Desktop/input.txt", "r", stdin);
int n, i;
cin >> n;
for (i = 1; i <= n; i++)
{
cin >> a[i];
}
sort (a + 1, a + n + 1);
BST root = buildTree (1, n);
queue<BST>q;
q.push (root);
i = 0;
while (!q.empty() )
{
BST t = q.front();
q.pop();
i++;
if (i < n)
cout << t->value << " ";
else
cout << t->value;
if (t->left != NULL)
q.push (t->left);
if (t->right != NULL)
q.push (t->right);
}
return 0;
}
数组:
#include <bits/stdc++.h>
#define x first
#define y second
using namespace std;
typedef long long ll;
int a[1024] = {0};
int ans[1024] = {0};
void buildTree (int start, int n, int index) // 从start开始的n个数字,找树根,存在下标index
{
if (n < 1)
{
return;
}
int full = 1, botton_cnt = 1;
while (full < n)
{
botton_cnt *= 2;
full += botton_cnt;
}
int lack = full - n;
int left_cnt = (full - 1) / 2;
if (lack > botton_cnt / 2)
{
left_cnt -= lack - botton_cnt / 2;
}
// [start,start+n]
ans[index] = a[start + left_cnt];
buildTree (start, left_cnt, index * 2);
buildTree (start + left_cnt + 1, n - left_cnt - 1, index * 2 + 1);
}
int main()
{
// system("chcp 65001");
std::ios::sync_with_stdio (false);
cin.tie (0);
cout.tie (0);
// freopen("C:/Users/zhaochen/Desktop/input.txt", "r", stdin);
int n, i;
cin >> n;
for (i = 1; i <= n; i++)
{
cin >> a[i];
}
sort (a + 1, a + n + 1);
buildTree (1, n, 1);
for (i = 1; i <= n; i++)
{
if (i == n)
cout << ans[i];
else
cout << ans[i] << " ";
}
return 0;
}
标签:Binary,Search,full,botton,Complete,int,cnt,start,left 来源: https://blog.csdn.net/m0_51800757/article/details/121065452