-
Notifications
You must be signed in to change notification settings - Fork 1
/
floorCeilingInBST.cpp
103 lines (86 loc) · 2.44 KB
/
floorCeilingInBST.cpp
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
#include <iostream>
#include <iomanip>
using namespace std;
// Data structure to store a Binary Search Tree node
struct Node {
int data;
Node *left, *right;
};
// Function to create a new binary tree node having given key
Node* newNode(int key)
{
Node* node = new Node;
node->data = key;
node->left = node->right = nullptr;
return node;
}
// Recursive function to insert a key into BST
Node* insert(Node* root, int key)
{
// if the root is null, create a new node and return it
if (root == nullptr)
return newNode(key);
// if given key is less than the root node, recur for left subtree
if (key < root->data)
root->left = insert(root->left, key);
// if given key is more than the root node, recur for right subtree
else
root->right = insert(root->right, key);
return root;
}
// Recursive function to find floor and ceil of a given key in a BST
// Note that floor and ceil is passed by reference to the function
void findFloorCeil(Node* root, int &floor, int &ceil, int key)
{
// base case
if (root == nullptr)
return;
// if node with key's value is found, both floor and ceil is equal
// to the current node
if (root->data == key)
{
floor = root->data;
ceil = root->data;
return;
}
// if given key is less than the root node, recur for left subtree
else if (key < root->data)
{
// update ceil to current node before recursing in left subtree
ceil = root->data;
findFloorCeil(root->left, floor, ceil, key);
}
// if given key is more than the root node, recur for right subtree
else
{
// update floor to current node before recursing in right subtree
floor = root->data;
findFloorCeil(root->right, floor, ceil, key);
}
}
int main()
{
/* Construct below tree
8
/ \
/ \
4 10
/ \ / \
/ \ / \
2 6 9 12
*/
int keys[] = { 8, 4, 2, 6, 10, 9, 12 };
Node* root = nullptr;
for (int key : keys)
root = insert(root, key);
// find Ceil and Floor for each key
for (int i = 0; i < 15; i++)
{
int floor=-1,ceil=-1;
findFloorCeil(root, floor, ceil, i);
cout << setw(2) << i << " --> ";
cout << setw(4) << (floor<=-1?-1:floor);
cout << setw(4) << (ceil<=-1?-1:ceil) << endl;
}
return 0;
}