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This is 9th part of java binary tree tutorial.

In this post, we will see about program to print all paths from root to leaf in a binary tree in java.

Below diagram will show all paths from root to leaf:

#### Algorithm:

- If node is null then return 0
- put node.data in array and increment len by 1.
- If encounterd leaf node(i.e. node.left is null and node.right is null) then print array.
- Recursively visit left subtree and right subtree

**Code for recursion will be:**

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// Prints all paths to leaf public static void printAllPathsToLeaf(TreeNode node, int[] path, int len) { if ( node == null ) return; // storing data in array path[len] = node.data; len++; if(node.left == null && node.right == null) { // leaf node is reached printArray(path,len); return; } printAllPathsToLeaf(node.left, path, len); printAllPathsToLeaf(node.right, path, len); } |

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package org.arpit.java2blog.binarytree; public class BinaryTreePrintAllPaths { public static class TreeNode { int data; TreeNode left; TreeNode right; TreeNode(int data) { this.data=data; } } // Prints all paths to leaf public static void printAllPathsToLeaf(TreeNode node, int[] path, int len) { if ( node == null ) return; // storing data in array path[len] = node.data; len++; if(node.left == null && node.right == null) { // leaf node is reached printArray(path,len); return; } printAllPathsToLeaf(node.left, path, len); printAllPathsToLeaf(node.right, path, len); } public static void main(String[] args) { // Creating a binary tree TreeNode rootNode=createBinaryTree(); System.out.println("Printing all paths from root to leaf :"); printAllPathsToLeaf(rootNode,new int[1000],0); } public static void printArray(int[] path,int len) { for (int i = 0; i < len; i++) { System.out.print(" "+path[i]); } System.out.println(); } public static TreeNode createBinaryTree() { TreeNode rootNode =new TreeNode(40); TreeNode node20=new TreeNode(20); TreeNode node10=new TreeNode(10); TreeNode node30=new TreeNode(30); TreeNode node60=new TreeNode(60); TreeNode node50=new TreeNode(50); TreeNode node70=new TreeNode(70); TreeNode node5=new TreeNode(5); TreeNode node55=new TreeNode(55); rootNode.left=node20; rootNode.right=node60; node20.left=node10; node20.right=node30; node60.left=node50; node60.right=node70; node10.left=node5; node50.right=node55; return rootNode; } } |

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Printing all paths from root to leaf : 40 20 10 5 40 20 30 40 60 50 55 40 60 70 |

## Java Binary tree tutorial:

- Binary tree in java
- Binary tree preorder traversal
- Binary tree postorder traversal
- Binary tree inorder traversal
- Binary tree level order traversal
- Binary tree spiral order traversal
- Binary tree reverse level order traversal
- Binary tree boundary traversal
- Print leaf nodes of binary tree
- Count leaf nodes in binary tree
- get maximum element in binary tree
- Print all paths from root to leaf in binary tree
- Print vertical sum of binary tree in java
- Get level of node in binary tree in java
- Lowest common ancestor(LCA) in binary tree in java

I appreciate your blog. Its really nice on java programming. Its a great tutorial for the beginners. Really liked it. Thank you for all the information.

hi

can u plz help me

actually this following part of your code is not working, giving an error

plz resolve this

•if(node.left == null && node.right == null) {

• // leaf node is reached

• printArray(path,len);

• return;

• }

•

thanks

Read more at https://www.java2blog.com/2014/08/print-all-paths-…

Thanks Tanu for pointing out. I have updated the code