Flashcards
Binary Search Tree Iterator
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- 1mplement 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.public class BSTIterator {
private Stack s;
public BSTIterator(TreeNode root) {
s = new Stack<>();
TreeNode cur = root;
while( cur != null){
s.push(cur);
if(cur.left != null)
cur = cur.left;
else
break;
}
}
/** @return whether we have a next smallest number */
public boolean hasNext() {
return (!s.isEmpty());
}
/** @return the next smallest number */
public int next() {
TreeNode cur = s.pop();
TreeNode node = cur;
if(cur.right != null ){
cur = cur.right;
while(cur != null){
s.push(cur);
if(cur.left != null){
cur = cur.left;
}else break;
}
}
return node.val;
}
}
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- Flashcards on Binary Search Tree Iterator, created by Suhas S on 28/03/2018.
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- Suhas S
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