Added solution

Author: avidLearnerInProgress

leaves_to_dll.cpp

@@ -0,0 +1,107 @@
+{
+#include<bits/stdc++.h>
+using namespace std;
+struct Node{
+	int data;
+	Node *left,*right;
+	
+	Node(int x){
+	    data = x;
+	    left = NULL;
+	    right = NULL;
+	}
+};
+void insert(Node *root, int a1,int a2, char lr){
+	if(root==NULL)
+		return;
+	if(root->data==a1){
+		switch(lr){
+			case 'L':root->left=new Node(a2);
+			break;
+			case 'R':root->right=new Node(a2);
+			break;
+		}
+	}
+	else{
+		insert(root->left, a1, a2, lr);
+		insert(root->right, a1, a2, lr);
+	}
+}
+Node *convertToDLL(Node *root,Node **head_ref);
+int main(){
+	int t;
+	cin>>t;
+	while(t--){
+		int n;
+		cin>>n;
+		Node *root=NULL;
+		while(n--){
+			int a1,a2;
+			char lr;
+			cin>>a1>>a2;
+			scanf(" %c",&lr);
+			if(root==NULL){
+				root=new Node(a1);
+				switch(lr){
+					case 'L':root->left=new Node(a2);
+					break;
+					case 'R':root->right=new Node(a2);
+					break;
+				}
+			}
+			else{
+				insert(root,a1,a2,lr);
+			}
+		}
+		
+		Node *head=NULL;
+		root=convertToDLL(root,&head);
+		
+		while(head->right!=NULL){
+			cout<<head->data<<" ";
+			head=head->right;
+		}
+		
+		cout<<head->data<<endl;
+		while(head!=NULL){
+			cout<<head->data<<" ";
+			head = head->left;
+		}
+		cout<<endl;
+	}
+}
+
+}
+/*This is a function problem.You only need to complete the function given below*/
+/*Complete the function below
+Node is as follows:
+struct Node{
+	int data;
+	Node *left,*right;
+	
+	Node(int x){
+	    data = x;
+	    left = NULL;
+	    right = NULL;
+	}
+};
+*/
+Node *convertToDLL(Node *root,Node **head_ref)
+{
+//add code here.
+
+    static Node* prev = NULL;
+    if(!root) return NULL;
+    convertToDLL(root->left, head_ref);
+    
+    if(!root->left && !root->right){ // if its a leaf node
+        if(!(*head_ref))
+            *head_ref = root;
+        else{
+            root->left = prev;
+            prev->right = root;
+        }
+        prev = root;
+    }
+    convertToDLL(root->right, head_ref);
+}