adding a Two Sum Program and Validate BST using cpp language

Program's_Contributed_By_Contributors/Cpp_Program/Two_Sum.cpp

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+#include <iostream>
+#include <sstream> // For stringstream to convert string to number
+#include <string>
+using namespace std;
+
+// Function to convert string input to a double and add two numbers
+double convertAndAdd(string input1, string input2)
+{
+    double num1, num2;
+
+    // Convert the first input to double
+    stringstream ss1(input1);
+    ss1 >> num1;
+
+    // Convert the second input to double
+    stringstream ss2(input2);
+    ss2 >> num2;
+
+    // Return the sum
+    return num1 + num2;
+}
+
+int main()
+{
+    string input1, input2;
+
+    // Taking two numbers as input from the user
+    cout << "Enter the first number: ";
+    cin >> input1;
+    cout << "Enter the second number: ";
+    cin >> input2;
+
+    // Add the numbers and display the result
+    double sum = convertAndAdd(input1, input2);
+    cout << "The sum of the two numbers is: " << sum << endl;
+
+    return 0;
+}

Program's_Contributed_By_Contributors/Cpp_Program/ValidateBST

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+#include<bits/stdc++.h>
+using namespace std;
+
+struct Node {
+    int data;
+    Node* left;
+    Node* right;
+    Node(int val) {
+        data = val;
+        left = right = NULL;
+    }
+};
+
+bool ValidateBSTChecker(Node* node, int min_val, int max_val) {
+    if (node == NULL) 
+        return true;
+
+    if (node->data < min_val || node->data > max_val)
+        return false;
+
+    return ValidateBSTChecker(node->left, min_val, node->data - 1) &&
+           ValidateBSTChecker(node->right, node->data + 1, max_val);
+}
+
+bool ValidateBST(Node* root) {
+    return ValidateBSTChecker(root, INT_MIN, INT_MAX);
+}
+
+int main() {
+    // Example usage
+    Node* root = new Node(4);
+    root->left = new Node(2);
+    root->right = new Node(5);
+    root->left->left = new Node(1);
+    root->left->right = new Node(3);
+
+    if (ValidateBST(root))
+        cout << "The tree is a valid BST.";
+    else
+        cout << "The tree is not a valid BST.";
+
+    return 0;
+}