C Program: Binary search Tree insertion with sorted in-order traversal

C Program to implement Tree Structure: Exercise-3 with Solution

Write a C program that extends the binary tree program to support the insertion of elements. This is in a way that maintains the binary search tree property.

Sample Solution:

C Code:

// Including necessary header files
#include <stdio.h>
#include <stdlib.h>

// Structure for a binary tree node
struct TreeNode {
    int data;
    struct TreeNode* left;
    struct TreeNode* right;
};

// Function to create a new node
struct TreeNode* createNode(int value) {
    struct TreeNode* newNode = (struct TreeNode*)malloc(sizeof(struct TreeNode));
    if (newNode != NULL) {
        newNode->data = value;
        newNode->left = NULL;
        newNode->right = NULL;
    }
    return newNode;
}

// Function to insert a node into the binary search tree
struct TreeNode* insertNode(struct TreeNode* root, int value) {
    if (root == NULL) {
        return createNode(value);
    }

    // Insert into the left subtree
    if (value < root->data) {
        root->left = insertNode(root->left, value);
    }
    // Insert into the right subtree
    else if (value > root->data) {
        root->right = insertNode(root->right, value);
    }

    return root;
}

// Function to perform in-order traversal and print elements in sorted order
void inOrderTraversal(struct TreeNode* root) {
    if (root != NULL) {
        inOrderTraversal(root->left);
        printf("%d ", root->data);
        inOrderTraversal(root->right);
    }
}

// Function to free the memory allocated for the binary tree
void freeTree(struct TreeNode* root) {
    if (root != NULL) {
        freeTree(root->left);
        freeTree(root->right);
        free(root);
    }
}

int main() {
    struct TreeNode* root = NULL;
    int nodeValue;
    char choice;

    // Insert nodes into the binary search tree
    do {
        printf("Input a value to insert into the binary search tree (enter 0 to stop): ");
        scanf("%d", &nodeValue);

        if (nodeValue != 0) {
            root = insertNode(root, nodeValue);
        }

    } while (nodeValue != 0);

    // Perform in-order traversal and print elements in sorted order
    printf("\nIn-order Traversal (Sorted Order) of the Binary Search Tree: ");
    inOrderTraversal(root);
    printf("\n");

    // Free allocated memory
    freeTree(root);

    return 0;
}

Output:

Input a value to insert into the binary search tree (enter 0 to stop): 72
Input a value to insert into the binary search tree (enter 0 to stop): 51
Input a value to insert into the binary search tree (enter 0 to stop): 42
Input a value to insert into the binary search tree (enter 0 to stop): 12
Input a value to insert into the binary search tree (enter 0 to stop): 10
Input a value to insert into the binary search tree (enter 0 to stop): 0

In-order Traversal (Sorted Order) of the Binary Search Tree: 10 12 42 51 72

Explanation:

In the exercise above,

The above C program creates a binary search tree (BST) and allows users to insert elements into it while maintaining the BST property. Here's a brief explanation.

• Data Structure:
• The program defines a structure TreeNode to represent a node in the binary search tree. Each node contains an integer data, and pointers to the left and right children (left and right).
• Node Creation:
• The createNode function dynamically allocates memory for a new node and initializes its data and pointers. It returns a pointer to the newly created node.
• Insertion:
• The insertNode function inserts a new node into the binary search tree while maintaining the BST property.
• If the value is less than the current node's data, it is inserted into the left subtree. If greater, it goes into the right subtree.
• In-order Traversal:
• The inOrderTraversal function performs an in-order traversal of the binary search tree, printing the elements in sorted order.
• Memory Management:
• The freeTree function frees the memory allocated for the binary search tree by recursively freeing each node.
• Main Function:
• In the main function, the program allows users to input values to be inserted into the binary search tree. The insertion continues until the user enters 0.
• After insertion, the program performs an in-order traversal, displaying the elements in sorted order.
• Finally, it frees the memory allocated for the binary search tree.

Flowchart:

C Programming Code Editor:

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