Deepest left leaf node in a binary tree | iterative approach
Given a Binary Tree, find the deepest leaf node that is left child of its parent. For example, consider the following tree. The deepest left leaf node is the node with value 9.
Examples:
Input :
1
/ \
2 3
/ / \
4 5 6
\ \
7 8
/ \
9 10
Output : 9
Recursive approach to this problem is discussed here
For iterative approach, idea is similar to Method 2 of level order traversal
The idea is to traverse the tree iteratively and whenever a left tree node is pushed to queue, check if it is leaf node, if it’s leaf node, then update the result. Since we go level by level, the last stored leaf node is deepest one,
C++
// CPP program to find deepest left leaf // node of binary tree #include <bits/stdc++.h> using namespace std; // tree node struct Node { int data; Node *left, *right; }; // returns a new tree Node Node* newNode(int data) { Node* temp = new Node(); temp->data = data; temp->left = temp->right = NULL; return temp; } // return the deepest left leaf node // of binary tree Node* getDeepestLeftLeafNode(Node* root) { if (!root) return NULL; // create a queue for level order traversal queue<Node*> q; q.push(root); Node* result = NULL; // traverse until the queue is empty while (!q.empty()) { Node* temp = q.front(); q.pop(); // Since we go level by level, the last // stored left leaf node is deepest one, if (temp->left) { q.push(temp->left); if (!temp->left->left && !temp->left->right) result = temp->left; } if (temp->right) q.push(temp->right); } return result; } // driver program int main() { // construct a tree Node* root = newNode(1); root->left = newNode(2); root->right = newNode(3); root->left->left = newNode(4); root->right->left = newNode(5); root->right->right = newNode(6); root->right->left->right = newNode(7); root->right->right->right = newNode(8); root->right->left->right->left = newNode(9); root->right->right->right->right = newNode(10); Node* result = getDeepestLeftLeafNode(root); if (result) cout << "Deepest Left Leaf Node :: " << result->data << endl; else cout << "No result, left leaf not found\n"; return 0; } |
Java
// Java program to find deepest left leaf // node of binary tree import java.util.*; class GFG { // tree node static class Node { int data; Node left, right; }; // returns a new tree Node static Node newNode(int data) { Node temp = new Node(); temp.data = data; temp.left = temp.right = null; return temp; } // return the deepest left leaf node // of binary tree static Node getDeepestLeftLeafNode(Node root) { if (root == null) return null; // create a queue for level order traversal Queue<Node> q = new LinkedList<>(); q.add(root); Node result = null; // traverse until the queue is empty while (!q.isEmpty()) { Node temp = q.peek(); q.remove(); // Since we go level by level, the last // stored left leaf node is deepest one, if (temp.left != null) { q.add(temp.left); if (temp.left.left == null && temp.left.right == null) result = temp.left; } if (temp.right != null) q.add(temp.right); } return result; } // Driver Code public static void main(String[] args) { // construct a tree Node root = newNode(1); root.left = newNode(2); root.right = newNode(3); root.left.left = newNode(4); root.right.left = newNode(5); root.right.right = newNode(6); root.right.left.right = newNode(7); root.right.right.right = newNode(8); root.right.left.right.left = newNode(9); root.right.right.right.right = newNode(10); Node result = getDeepestLeftLeafNode(root); if (result != null) System.out.println("Deepest Left Leaf Node :: " + result.data); else System.out.println("No result, " + "left leaf not found"); } } // This code is contributed by Rajput-Ji |
Python3
# Python3 program to find deepest # left leaf Binary search Tree _MIN = -2147483648_MAX = 2147483648 # Helper function that allocates a new # node with the given data and None # left and right poers. class newnode: # Constructor to create a new node def __init__(self, data): self.data = data self.left = None self.right = None # utility function to return deepest # left leaf node def getDeepestLeftLeafNode(root) : if (not root): return None # create a queue for level # order traversal q = [] q.append(root) result = None # traverse until the queue is empty while (len(q)): temp = q[0] q.pop(0) if (temp.left): q.append(temp.left) if (not temp.left.left and not temp.left.right): result = temp.left # Since we go level by level, # the last stored right leaf # node is deepest one if (temp.right): q.append(temp.right) return result # Driver Code if __name__ == '__main__': # create a binary tree root = newnode(1) root.left = newnode(2) root.right = newnode(3) root.left.Left = newnode(4) root.right.left = newnode(5) root.right.right = newnode(6) root.right.left.right = newnode(7) root.right.right.right = newnode(8) root.right.left.right.left = newnode(9) root.right.right.right.right = newnode(10) result = getDeepestLeftLeafNode(root) if result: print("Deepest Left Leaf Node ::", result.data) else: print("No result, Left leaf not found") # This code is contributed by # Shubham Singh(SHUBHAMSINGH10) |
C#
// C# program to find deepest left leaf // node of binary tree using System; using System.Collections.Generic; class GFG { // tree node class Node { public int data; public Node left, right; }; // returns a new tree Node static Node newNode(int data) { Node temp = new Node(); temp.data = data; temp.left = temp.right = null; return temp; } // return the deepest left leaf node // of binary tree static Node getDeepestLeftLeafNode(Node root) { if (root == null) return null; // create a queue for level order traversal Queue<Node> q = new Queue<Node>(); q.Enqueue(root); Node result = null; // traverse until the queue is empty while (q.Count != 0) { Node temp = q.Peek(); q.Dequeue(); // Since we go level by level, the last // stored left leaf node is deepest one, if (temp.left != null) { q.Enqueue(temp.left); if (temp.left.left == null && temp.left.right == null) result = temp.left; } if (temp.right != null) q.Enqueue(temp.right); } return result; } // Driver Code public static void Main(String[] args) { // construct a tree Node root = newNode(1); root.left = newNode(2); root.right = newNode(3); root.left.left = newNode(4); root.right.left = newNode(5); root.right.right = newNode(6); root.right.left.right = newNode(7); root.right.right.right = newNode(8); root.right.left.right.left = newNode(9); root.right.right.right.right = newNode(10); Node result = getDeepestLeftLeafNode(root); if (result != null) Console.WriteLine("Deepest Left Leaf Node :: " + result.data); else Console.WriteLine("No result, " + "left leaf not found"); } } // This code is contributed by Rajput-Ji |
Output:
Deepest Left Leaf Node :: 9
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