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package DataStructures.Trees;
public class ValidBSTOrNot {
class Node {
int data;
Node left, right;
public Node(int item) {
data = item;
left = right = null;
}
}
// Root of the Binary Tree
/* can give min and max value according to your code or
can write a function to find min and max value of tree. */
/* returns true if given search tree is binary
search tree (efficient version) */
boolean isBST(Node root) {
return isBSTUtil(root, Integer.MIN_VALUE, Integer.MAX_VALUE);
}
/* Returns true if the given tree is a BST and its
values are >= min and max) return false;
/* otherwise check the subtrees recursively
tightening the min/max constraints */
// Allow only distinct values
return (isBSTUtil(node.left, min, node.data - 1) && isBSTUtil(node.right, node.data + 1, max));
}
}