Create Least_Common_Ancestor.cpp

Trees/Least_Common_Ancestor.cpp

@@ -0,0 +1,59 @@
+// A recursive CPP program to find Least Common Ancestor of two nodes n1 and n2. 
+#include <bits/stdc++.h> 
+using namespace std; 
+
+class node 
+{ 
+	public: 
+	int data; 
+	node* left, *right; 
+}; 
+
+// Function to find LCA of n1 and n2. The function assumes that both n1 and n2 are present in BST
+node *lca(node* root, int n1, int n2) 
+{ 
+	if (root == NULL) return NULL; 
+
+	// If both n1 and n2 are smaller than root, then LCA lies in left 
+	if (root->data > n1 && root->data > n2) 
+		return lca(root->left, n1, n2); 
+
+	// If both n1 and n2 are greater than root, then LCA lies in right 
+	if (root->data < n1 && root->data < n2) 
+		return lca(root->right, n1, n2); 
+
+	return root; 
+} 
+
+// function that allocates a new node with the given data.
+node* newNode(int data) 
+{ 
+	node* Node = new node(); 
+	Node->data = data; 
+	Node->left = Node->right = NULL; 
+	return(Node); 
+} 
+
+int main() 
+{ 
+	node *root = newNode(20); 
+	root->left = newNode(8); 
+	root->right = newNode(22); 
+	root->left->left = newNode(4); 
+	root->left->right = newNode(12); 
+	root->left->right->left = newNode(10); 
+	root->left->right->right = newNode(14); 
+
+	int n1 = 10, n2 = 14; 
+	node *t = lca(root, n1, n2); 
+	cout << "LCA of " << n1 << " and " << n2 << " is " << t->data<<endl; 
+
+    n1 = 14, n2 = 8;  
+    t = lca(root, n1, n2);  
+    cout<<"LCA of " << n1 << " and " << n2 << " is " << t->data << endl;  
+
+    n1 = 10, n2 = 22;  
+    t = lca(root, n1, n2);  
+    cout << "LCA of " << n1 << " and " << n2 << " is " << t->data << endl;  
+	return 0; 
+}