Final answer:
The countDepthK method counts the number of nodes at a specific depth k in a BinaryTree. A recursive approach can be used to traverse the tree and increment a count when the desired depth is reached.
Step-by-step explanation:
The countDepthK method in a BinaryTree class involves writing an algorithm to traverse the tree and count the number of nodes at a specific depth k. Depth of a node is defined by the number of edges from the root to the node. To count the nodes at depth k, we can perform a depth-first search or a breadth-first search that keeps track of the current depth. If the current depth equals k, we increment our count. The method will return the count if it finds nodes at depth k or zero if k is greater than the depth of the tree.
Example Implementation
To implement countDepthK, here is an example method signature and a recursive approach:
int countDepthK(BinaryTreeNode root, int k) {
if (root == null)
return 0;
if (k == 0)
return 1;
else
return countDepthK(root.left, k - 1) + countDepthK(root.right, k - 1);
}
To invoke this method, you would call it with the root of your binary tree and the depth k you are interested in. Remember to handle the base cases, when the node is null and when k is zero, as they will be essential in correctly calculating the number of nodes.