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IsBST.java
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72 lines (65 loc) · 2.07 KB
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/**
* determine if a given binary tree is a binary search tree.
*/
public class IsBST {
public static void main(String[] args) {
Node root = new Node(10);
Node node5 = new Node(5);
Node node15 = new Node(15);
Node node6 = new Node(6);
Node node20 = new Node(20);
Node node3 = new Node(3);
Node node12 = new Node(12);
root.insert(node5);
root.insert(node6);
root.insert(node15);
root.insert(node20);
root.insert(node3);
root.insert(node12);
System.out.println(isBST(root, Integer.MIN_VALUE, Integer.MAX_VALUE));
System.out.println(isBST1(root, Integer.MIN_VALUE));
BTreeIterator treeIterator = new BTreeIterator(root);
while (treeIterator.hasNext()){
Node next = treeIterator.inOrderNext();
System.out.print(next.value + " ");
}
System.out.println();
while (treeIterator.hasNextPostOrder()){
Node next = treeIterator.postOrderNext();
System.out.print(next.value + " ");
}
System.out.println();
treeIterator.reset();
while (treeIterator.hasNextPreOrder()){
Node next = treeIterator.preOrderNext();
System.out.print(next.value + " ");
}
System.out.println();
}
public static boolean isBST(Node node, int min, int max) {
if (node == null) {
return true;
}
if ((min < node.value) && (node.value < max)) {
return isBST(node.left, min, node.value) &&
isBST(node.right, node.value, max);
} else {
return false;
}
}
public static boolean isBST1(Node node, int prev) {
if (node == null) {
return true;
}
if (isBST1(node.left, prev)) {
if (node.value > prev) {
prev = node.value;
return isBST1(node.right, prev);
} else {
return false;
}
} else {
return false;
}
}
}