Given a binary tree with distinct nodes(no two nodes have the same data values). The problem is to get the path from root to a given node x.

Examples:

Input :          1
/   \
2     3
/  \   /  \
4    5  6   7
x = 5
Output : 1->2->5

Solution

Approach 1: Recursive

public boolean getRootToNodePath(TreeNode root, TreeNode node, 
                                 List<TreeNode> path){
        if(root == null){
            return false;
        }

        // visit - add to path
        path.add(root);

        if(root.val == node.val){
            path.add(root);
            return true;
        }
       
        // search in left and right subtree
        if(getRootToNodePath(root.left, node, path) || 
           getRootToNodePath(root.right, node, path)){
            return true;
        }

        // visit - remove from path
        path.remove(path.size()-1);

        return false;
}

Approach 2: Iterative

References