46 lines
1.3 KiB
Java
46 lines
1.3 KiB
Java
package DataStructures.Trees;
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import DataStructures.Trees.BinaryTree.Node;
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/**
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* Given a sorted array. Create a balanced binary search tree from it.
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*
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* Steps:
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* 1. Find the middle element of array. This will act as root
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* 2. Use the left half recursively to create left subtree
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* 3. Use the right half recursively to create right subtree
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*/
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public class CreateBSTFromSortedArray {
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public static void main(String[] args) {
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test(new int[]{});
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test(new int[]{1, 2, 3});
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test(new int[]{1, 2, 3, 4, 5});
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test(new int[]{1, 2, 3, 4, 5, 6, 7});
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}
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private static void test(int[] array) {
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BinaryTree root = new BinaryTree(createBst(array, 0, array.length - 1));
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System.out.println("\n\nPreorder Traversal: ");
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root.preOrder(root.getRoot());
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System.out.println("\nInorder Traversal: ");
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root.inOrder(root.getRoot());
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System.out.println("\nPostOrder Traversal: ");
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root.postOrder(root.getRoot());
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}
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private static Node createBst(int[] array, int start, int end) {
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// No element left.
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if (start > end) {
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return null;
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}
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int mid = start + (end - start) / 2;
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// middle element will be the root
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Node root = new Node(array[mid]);
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root.left = createBst(array, start, mid - 1);
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root.right = createBst(array, mid + 1, end);
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return root;
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}
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}
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