private static BalanceStatusWithHeight CheckBalanced(BinaryTreeNode<Integer> tree) {
if (tree == null) {
return new BalanceStatusWithHeight(true, -1); // Base case.
}
BalanceStatusWithHeight leftResult = CheckBalanced(tree.getLeft());
if (leftResult.balanced == false) {
return leftResult; // Left subtree is not balanced.
}
BalanceStatusWithHeight rightResult = CheckBalanced(tree.getRight());
if (rightResult.balanced == false) {
return rightResult; // Right subtree is not balanced.
}
boolean isBalanced = Math.abs(leftResult.height - rightResult.height) <= 1;
int height = Math.max(leftResult.height, rightResult.height) + 1;
return new BalanceStatusWithHeight(isBalanced, height);
}
private static boolean areKeysInRange(
BinaryTreeNode<Integer> tree, Integer lower, Integer upper) {
if (tree == null) {
return true;
} else if (Integer.compare(tree.getData(), lower) < 0
|| Integer.compare(tree.getData(), upper) > 0) {
return false;
}
return areKeysInRange(tree.getLeft(), lower, tree.getData())
&& areKeysInRange(tree.getRight(), tree.getData(), upper);
}
public static void main(String[] args) {
// balanced binary tree test
// 3
// 2 5
// 1 4 6
BinaryTreeNode<Integer> tree = new BinaryTreeNode<>();
tree.setLeft(new BinaryTreeNode<Integer>());
tree.getLeft().setLeft(new BinaryTreeNode<Integer>());
tree.setRight(new BinaryTreeNode<Integer>());
tree.getRight().setLeft(new BinaryTreeNode<Integer>());
tree.getRight().setRight(new BinaryTreeNode<Integer>());
assert (isBalanced(tree));
System.out.println(isBalanced(tree));
tree = new BinaryTreeNode<>();
tree.setLeft(new BinaryTreeNode<Integer>());
tree.getLeft().setLeft(new BinaryTreeNode<Integer>());
assert (!isBalanced(tree));
System.out.println(isBalanced(tree));
}
public static void main(String[] args) {
// 3
// 2 5
// 1 4 6
BinaryTreeNode<Integer> tree = new BinaryTreeNode<>(3);
tree.setLeft(new BinaryTreeNode<>(2));
tree.getLeft().setLeft(new BinaryTreeNode<>(1));
tree.setRight(new BinaryTreeNode<>(5));
tree.getRight().setLeft(new BinaryTreeNode<>(4));
tree.getRight().setRight(new BinaryTreeNode<>(6));
// should output true.
assert isBinaryTreeBST(tree);
System.out.println(isBinaryTreeBST(tree));
// 10
// 2 5
// 1 4 6
tree.setData(10);
// should output false.
assert !isBinaryTreeBST(tree);
System.out.println(isBinaryTreeBST(tree));
// should output true.
assert isBinaryTreeBST(null);
System.out.println(isBinaryTreeBST(null));
}