Wednesday, December 31, 2014

Binary Search Tree Iterator

mplement an iterator over a binary search tree (BST). Your iterator will be initialized with the root node of a BST.
Calling next() will return the next smallest number in the BST.
Note: next() and hasNext() should run in average O(1) time and uses O(h) memory, where h is the height of the tree.

Use a stack to store all left child of the tree (pushNode()). When calling next() method, pop() the tail of the stack. If the node has a right child, store all left children of the right child (pushNode(right)).




public class BSTIterator {
    
    private Stack stack;

    public BSTIterator(TreeNode root) {
        stack = new Stack ();
        pushNode(root);
        
    }
    private void pushNode(TreeNode root) {
        while (root != null) {
            stack.push(root);
            root = root.left;
        }
    }
    

    /** @return whether we have a next smallest number */
    public boolean hasNext() {
        return !stack.isEmpty();
    }

    /** @return the next smallest number */
    public int next() {
        if (stack.isEmpty()) {
            throw new Error("All nodes have been visited");
        }
        TreeNode curr = stack.pop();
        if(curr.right != null) {
            pushNode(curr.right);
        }
        return curr.val;
    }
}

1 comment:


  1. The development of artificial intelligence (AI) has propelled more programming architects, information scientists, and different experts to investigate the plausibility of a vocation in machine learning. Notwithstanding, a few newcomers will in general spotlight a lot on hypothesis and insufficient on commonsense application. IEEE final year projects on machine learning In case you will succeed, you have to begin building machine learning projects in the near future.

    Projects assist you with improving your applied ML skills rapidly while allowing you to investigate an intriguing point. Furthermore, you can include projects into your portfolio, making it simpler to get a vocation, discover cool profession openings, and Final Year Project Centers in Chennai even arrange a more significant compensation.


    Data analytics is the study of dissecting crude data so as to make decisions about that data. Data analytics advances and procedures are generally utilized in business ventures to empower associations to settle on progressively Python Training in Chennai educated business choices. In the present worldwide commercial center, it isn't sufficient to assemble data and do the math; you should realize how to apply that data to genuine situations such that will affect conduct. In the program you will initially gain proficiency with the specialized skills, including R and Python dialects most usually utilized in data analytics programming and usage; Python Training in Chennai at that point center around the commonsense application, in view of genuine business issues in a scope of industry segments, for example, wellbeing, promoting and account.

    ReplyDelete