41 lines
1.1 KiB
Java
41 lines
1.1 KiB
Java
package DataStructures.Trees;
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public class ValidBSTOrNot {
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class Node {
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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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data = item;
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left = right = null;
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}
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}
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// Root of the Binary Tree
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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(Node root) {
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return isBSTUtil(root, Integer.MIN_VALUE, 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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/* an empty tree is BST */
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if (node == null) 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) 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) && isBSTUtil(node.right, node.data + 1, max));
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}
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}
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