数据结构_顺序存储二叉树

基本说明

从数据存储来看，数组存储方式和树的存储方式可以相互转换。

特点

• 只考虑完全二叉树
• 第n个元素的左子节点为 2n + 1
• 第n个元素的右子节点为 2n + 2
• 第n个元素的父节点为 (n-1) / 2
• n表示树从顶层向下，从左往右依次编号，对应数组中的索引

代码实现

public class ArrayBinaryTree {
	private int[] arr;

	public ArrayBinaryTree(int[] arr) {
		super();
		this.arr = arr;
	}

	/**
	 * 前序遍历数组
	 * @param index
	 */
	public void preOrder(int index) {
		if (arr == null || arr.length == 0) {
			System.out.println("null");
		}
		System.out.print(arr[index]);
		int leftIndex = index * 2 + 1;
		int rightIndex = index * 2 + 2;
		if (leftIndex < arr.length) {
			preOrder(leftIndex);
		}
		if (rightIndex < arr.length) {
			preOrder(rightIndex);
		}
	}

	/**
	 * 中序遍历
	 * @param index
	 */
	public void infixOrder(int index) {
		if (arr == null || arr.length == 0) {
			System.out.println("null");
		}
		int leftIndex = index * 2 + 1;
		int rightIndex = index * 2 + 2;
		if (leftIndex < arr.length) {
			infixOrder(leftIndex);
		}
		System.out.print(arr[index]);
		if (rightIndex < arr.length) {
			infixOrder(rightIndex);
		}
	}

	/**
	 * 后序遍历
	 * @param index
	 */
	public void postOrder(int index) {
		if (arr == null || arr.length == 0) {
			System.out.println("null");
		}
		int leftIndex = index * 2 + 1;
		int rightIndex = index * 2 + 2;
		if (leftIndex < arr.length) {
			postOrder(leftIndex);
		}
		if (rightIndex < arr.length) {
			postOrder(rightIndex);
		}
		System.out.print(arr[index]);
	}
}