for http://www.geeksforgeeks.org/print-nodes-distance-k-leaf-node/

print-tree-with-distance.py

#!/usr/bin/env python

class TreeNode:
    def __init__(self, val):
        self.val = val
        self.left = None
        self.right = None

def printTreeWithDistance(root, k):
    def impl(root, path):
        if root == None:
            if len(path) >= k:
                path[-k] = True
            return
        path.append(False)
        impl(root.left, path)
        impl(root.right, path)
        v = path.pop()
        if v:
            print root.val
    impl(root, [])

if __name__ == '__main__':
    root = TreeNode(10)
    root.right = TreeNode(11)
    root.left = TreeNode(9)
    root.left.right = TreeNode(8)
    root.left.left = TreeNode(7)
    root.left.left.right = TreeNode(6)
    root.left.left.left = TreeNode(5)
    root.left.left.left.right = TreeNode(4)
    printTreeWithDistance(root, 3)