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arrayToBinaryTree.java
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68 lines (53 loc) · 1.71 KB
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// Java program to print BST in given range
// A binary tree node
//Runtime: O(n)
// T(n) = 2T(n/2) + C
// T(n) --> Time taken for an array of size n
// C --> Constant (Finding middle of array and linking root to left
// and right subtrees take constant time)
class Node {
int data;
Node left, right;
Node(int d) {
data = d;
left = right = null;
}
}
class BinaryTree {
static Node root;
/* A function that constructs Balanced Binary Search Tree
from a sorted array */
Node sortedArrayToBST(int arr[], int start, int end) {
/* Base Case */
if (start > end) {
return null;
}
/* Get the middle element and make it root */
int mid = (start + end) / 2;
Node node = new Node(arr[mid]);
/* Recursively construct the left subtree and make it
left child of root */
node.left = sortedArrayToBST(arr, start, mid - 1);
/* Recursively construct the right subtree and make it
right child of root */
node.right = sortedArrayToBST(arr, mid + 1, end);
return node;
}
/* A utility function to print preorder traversal of BST */
void preOrder(Node node) {
if (node == null) {
return;
}
System.out.print(node.data + " ");
preOrder(node.left);
preOrder(node.right);
}
public static void main(String[] args) {
BinaryTree tree = new BinaryTree();
int arr[] = new int[]{1, 2, 3, 4, 5, 6, 7};
int n = arr.length;
root = tree.sortedArrayToBST(arr, 0, n - 1);
System.out.println("Preorder traversal of constructed BST");
tree.preOrder(root);
}
}