BST Find Minimum Element in DSA C++ - Build from Scratch

BST Find Minimum Element

📖 Scenario: You are working with a Binary Search Tree (BST) that stores numbers. You want to find the smallest number in this tree. This is useful when you want to know the minimum value quickly, like finding the earliest date or lowest price.

🎯 Goal: Build a simple BST with some numbers, then write code to find and print the minimum element in the BST.

📋 What You'll Learn

Create a BST node structure with integer data and left/right pointers

Manually create a BST with these exact values: 15, 10, 20, 8, 12, 17, 25

Write a function called findMin that returns the minimum value in the BST

Print the minimum value found by findMin

💡 Why This Matters

🌍 Real World

Finding minimum values quickly is useful in many applications like scheduling, price comparisons, and searching sorted data.

💼 Career

Understanding BSTs and how to find minimum or maximum elements is a common task in software engineering interviews and real-world coding.

1

Create BST Node Structure and Build Tree

Create a struct called Node with an int data, and two pointers Node* left and Node* right. Then create the BST root node with value 15. Manually add nodes with values 10, 20, 8, 12, 17, and 25 to form the BST.

DSA C++

// Define struct Node
// Create root node with value 15
// Add nodes 10, 20, 8, 12, 17, 25 to build BST
// Your code here

Hint

Remember, in a BST, left child nodes have smaller values and right child nodes have larger values than the parent.

2

Declare the findMin Function

Declare a function called findMin that takes a Node* parameter named root and returns an int. This function will find the minimum value in the BST.

DSA C++

struct Node {
    int data;
    Node* left;
    Node* right;
};

Node* root = new Node{15, nullptr, nullptr};
root->left = new Node{10, nullptr, nullptr};
root->right = new Node{20, nullptr, nullptr};
root->left->left = new Node{8, nullptr, nullptr};
root->left->right = new Node{12, nullptr, nullptr};
root->right->left = new Node{17, nullptr, nullptr};
root->right->right = new Node{25, nullptr, nullptr};

int findMin(Node* root);
// Your code here

Hint

Just write the function header for now. The function will return an integer and take a pointer to Node.

3

Implement the findMin Function

Implement the findMin function to find the minimum value in the BST. Use a loop to go left until root->left is nullptr. Return the data of the leftmost node.

DSA C++

struct Node {
    int data;
    Node* left;
    Node* right;
};

Node* root = new Node{15, nullptr, nullptr};
root->left = new Node{10, nullptr, nullptr};
root->right = new Node{20, nullptr, nullptr};
root->left->left = new Node{8, nullptr, nullptr};
root->left->right = new Node{12, nullptr, nullptr};
root->right->left = new Node{17, nullptr, nullptr};
root->right->right = new Node{25, nullptr, nullptr};

int findMin(Node* root) {
    // Your code here
}

Hint

Keep moving to the left child until there is no left child. Then return that node's data.

4

Print the Minimum Element

Write a std::cout statement to print the minimum element found by calling findMin(root). Print exactly: Minimum element: X where X is the minimum value.

DSA C++

struct Node {
    int data;
    Node* left;
    Node* right;
};

Node* root = new Node{15, nullptr, nullptr};
root->left = new Node{10, nullptr, nullptr};
root->right = new Node{20, nullptr, nullptr};
root->left->left = new Node{8, nullptr, nullptr};
root->left->right = new Node{12, nullptr, nullptr};
root->right->left = new Node{17, nullptr, nullptr};
root->right->right = new Node{25, nullptr, nullptr};

int findMin(Node* root) {
    while (root->left != nullptr) {
        root = root->left;
    }
    return root->data;
}

#include 

int main() {
    // Your code here
}

Hint

Call findMin(root) and print the result with std::cout. Use the exact format: Minimum element: X.