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M173_BSTIterator
37 lines (31 loc) · 920 Bytes
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M173_BSTIterator
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class BSTIterator {
List<Integer> result = new ArrayList<>();
public BSTIterator(TreeNode root) {
result = inorderTraversal(root, result);
}
/** @return the next smallest number */
public int next() {
return result.remove(0);
}
/** @return whether we have a next smallest number */
public boolean hasNext() {
if(result.size()==0)
return false;
else
return true;
}
public List<Integer> inorderTraversal(TreeNode root, List<Integer> al){
if(root==null)
return al;
inorderTraversal(root.left, al);
al.add(root.val);
inorderTraversal(root.right, al);
return al;
}
}
/**
* Your BSTIterator object will be instantiated and called as such:
* BSTIterator obj = new BSTIterator(root);
* int param_1 = obj.next();
* boolean param_2 = obj.hasNext();
*/