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 or equal to the node's key.
- The right subtree of a node contains only nodes with keys greater than the node's key.
- Both the left and right subtrees must also be binary search trees.
Insert a sequence of numbers into an initially empty binary search tree. Then you are supposed to count the total number of nodes in the lowest 2 levels of the resulting tree.
Input Specification:
Each input file contains one test case. For each case, the first line gives a positive integer N (≤1000) which is the size of the input sequence. Then given in the next line are the Nintegers in [−10001000] which are supposed to be inserted into an initially empty binary search tree.
Output Specification:
For each case, print in one line the numbers of nodes in the lowest 2 levels of the resulting tree in the format:
n1 + n2 = n
where n1 is the number of nodes in the lowest level, n2 is that of the level above, and n is the sum.
Sample Input:
9
25 30 42 16 20 20 35 -5 28
Sample Output:
2 + 4 = 6
#include<iostream>
#include<cstring>
#include<vector>
#include<queue>
using namespace std;
struct node
{
int data;
node * lchild;
node * rchild;
};
int a[1001] = {0};
node * creat_tree(node * root, int data){
if(root == NULL){
root = new node();
root -> data = data;
root -> lchild = root -> rchild = NULL;
}else if (data <= root -> data)
{
root -> lchild = creat_tree(root -> lchild, data);
}else
{
root -> rchild = creat_tree(root -> rchild, data);
}
return root;
}
void level_order(node * tree){
queue<node *> que;
que.push(tree);
int hight = 0;
while (!que.empty())
{
int z = que.size();
a[hight] = z;
while (z--)
{
if(que.front() -> lchild != NULL){
que.push(que.front() -> lchild);
}
if(que.front() -> rchild != NULL){
que.push(que.front() -> rchild);
}
que.pop();
}
hight++;
}
}
int main(){
int n;
cin >> n;
vector<int> vec(n);
node * t = NULL;
for(int i = 0; i < n; i++){
scanf("%d", &vec[i]);
t = creat_tree(t, vec[i]);
}
level_order(t);
int flag;
for(int i = 0; i < 1000; i++){
if(a[i]){
flag = i;
}
}
printf("%d + %d = %d\n", a[flag], a[flag - 1], a[flag] + a[flag - 1]);
return 0;
}