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Code Binary Search Tree

# Find kth smallest element in BST c

C program for Find kth smallest element in BST. Here more solutions.

``````// Include header file
#include <stdio.h>
#include <stdlib.h>

// C program for
// K’th smallest element in Binary Search Tree
typedef struct TreeNode
{
// Define useful field of TreeNode
int data;
struct TreeNode * left;
struct TreeNode * right;
}TreeNode;

TreeNode * getTreeNode(int data)
{
// Create dynamic memory of TreeNode
TreeNode * ref = (TreeNode * ) malloc(sizeof(TreeNode));
if (ref == NULL)
{
// Failed to create memory
return NULL;
}
ref->data = data;
ref->left = NULL;
ref->right = NULL;
return ref;
}
typedef struct BinarySearchTree
{
// Define useful field of BinarySearchTree
struct TreeNode * root;
int counter;
struct TreeNode * element;
}BinarySearchTree;

BinarySearchTree * getBinarySearchTree()
{
// Create dynamic memory of BinarySearchTree
BinarySearchTree * ref = (BinarySearchTree * ) malloc(sizeof(BinarySearchTree));
if (ref == NULL)
{
// Failed to create memory
return NULL;
}
ref->root = NULL;
return ref;
}
// Insert a node element
TreeNode * insert(BinarySearchTree * ref,
TreeNode * node, int data)
{
if (node != NULL)
{
if (node->data >= data)
{
// When new element is smaller or equal to current node
node->left = insert(ref,node->left, data);
}
else
{
// When new element is higher to current node
node->right = insert(ref, node->right, data);
}
// Important to manage new node
return node;
}
else
{
return getTreeNode(data);
}
}
// Find the kth smallest node in BST
void findKthSmallest(BinarySearchTree * ref,
TreeNode * node, int k)
{
if (node != NULL)
{
// Visit left subtree
findKthSmallest(ref, node->left, k);
if (ref->counter == k)
{
// Stop recursion
return;
}
if (ref->element == NULL || ref->element->data < node->data)
{
// Modified counter variable by one
ref->counter++;
// Collect possible result
ref->element = node;
}
// Visit right subtree
findKthSmallest(ref, node->right, k);
}
}
void printKthSsmallest(BinarySearchTree * ref, int k)
{
if (k <= 0)
{
// When given k is not valid positive values
printf("Invalid node position %d\n", k);
}
else if (ref->root == NULL)
{
// When BST are no have elements
printf("Empty Binary Search Tree");
}
else
{
// Reset values
ref->counter = 0;
ref->element = NULL;
// Find result
findKthSmallest(ref, ref->root, k);
if (ref->counter < k)
{
// If In case given kth smallest node are
// Not exist in binary search tree, then
printf("Given %d smallest node are not exist %d\n", k, ref->counter);
}
else
{
printf("[%d] smallest node : %d\n", k,ref->element->data);
}
}
}
// Handle request to add new node
void addNode(BinarySearchTree * ref, int key)
{
ref->root = insert(ref, ref->root, key);
}
int main()
{
BinarySearchTree * tree = getBinarySearchTree();
/*
Make Tree
----------
7
/ \
/   \
4     9
/ \   / \
3   5 8   10
/
4
*/
// Testing
printKthSsmallest(tree, 6);
printKthSsmallest(tree, 4);
printKthSsmallest(tree, 3);
return 0;
}``````

Output

``````[6] smallest node : 9
[4] smallest node : 7
[3] smallest node : 5``````

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