62 lines
1.6 KiB
Java
62 lines
1.6 KiB
Java
class Node
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{
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int data;
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Node left, right;
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public Node(int item)
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{
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data = item;
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left = right = null;
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}
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}
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public class ValidBSTOrNot
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{
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//Root of the Binary Tree
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Node root;
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/* can give min and max value according to your code or
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can write a function to find min and max value of tree. */
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/* returns true if given search tree is binary
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search tree (efficient version) */
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boolean isBST() {
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return isBSTUtil(root, Integer.MIN_VALUE,
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Integer.MAX_VALUE);
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}
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/* Returns true if the given tree is a BST and its
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values are >= min and <= max. */
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boolean isBSTUtil(Node node, int min, int max)
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{
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/* an empty tree is BST */
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if (node == null)
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return true;
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/* false if this node violates the min/max constraints */
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if (node.data < min || node.data > max)
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return false;
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/* otherwise check the subtrees recursively
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tightening the min/max constraints */
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// Allow only distinct values
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return (isBSTUtil(node.left, min, node.data-1) &&
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isBSTUtil(node.right, node.data+1, max));
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}
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/* Driver program to test above functions */
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public static void main(String args[])
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{
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ValidBSTOrNot tree = new ValidBSTOrNot();
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tree.root = new Node(4);
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tree.root.left = new Node(2);
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tree.root.right = new Node(5);
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tree.root.left.left = new Node(1);
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tree.root.left.right = new Node(3);
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if (tree.isBST())
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System.out.println("IS BST");
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else
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System.out.println("Not a BST");
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}
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} |