day13-Java（二叉树的建立）

二叉树的建立

前言一、二叉树构造二、代码与数据测试

今天的代码比较简单，经过前两天的代码的洗礼，这段代码属于是易理解代码了。

构造函数的参数为两个数组，一个存储的是节点数据，一个是存储节点索引位置。如下图：

创建树的节点，并将paraDataArray中数据存储到节点中。代码如下：

for (int i = 0; i < tempNumNodes; i++) {
			tempAllNodes[i] = new BinaryCharTree(paraDataArray[i]);
		} // Of for i

此时节点是一个一个离散的状态并没有呈树形，接下来就是通过另一个数组（存储节点索引位置的数组）来判断各个节点的“父子”关系，从而连接各个节点形成树形。

	public BinaryCharTree(char[] paraDataArray, int[] paraIndicesArray) {
		// Step 1. Use a sequential list to store all nodes.
		int tempNumNodes = paraDataArray.length;
		BinaryCharTree[] tempAllNodes = new BinaryCharTree[tempNumNodes];
		for (int i = 0; i < tempNumNodes; i++) {
			tempAllNodes[i] = new BinaryCharTree(paraDataArray[i]);
		} // Of for i
		
		// Step 2. link these nodes.
		for (int i = 1; i < tempNumNodes; i++) {
			for (int j = 0; j < i; j++) {
				System.out.println("indices " + paraIndicesArray[j] + " vs. " + paraIndicesArray[i]);
				if (paraIndicesArray[i] == paraIndicesArray[j] * 2 + 1) {
					tempAllNodes[j].leftChild = tempAllNodes[i];
					System.out.println("linking " + j + " with " + i);
					break;
				} else if (paraIndicesArray[i] == paraIndicesArray[j] * 2 + 2) {
					tempAllNodes[j].rightChild = tempAllNodes[i];
					System.out.println("linking " + j + " with " + i);
					break;
				} // Of if
			} // Of for j
		} // Of for i
		
		// Step 3. The root is the first node.
		value = tempAllNodes[0].value;
		leftChild = tempAllNodes[0].leftChild;
		rightChild = tempAllNodes[0].rightChild;
	} // Of the second constructor

	
	public static void main(String args[]) {
		BinaryCharTree tempTree = manualConstructTree();
		System.out.println("rnPreorder visit:");
		tempTree.preOrderVisit();
		System.out.println("rnIn-order visit:");
		tempTree.inOrderVisit();
		System.out.println("rnPost-order visit:");
		tempTree.postOrderVisit();

		System.out.println("rnrnThe depth is: " + tempTree.getDepth());
		System.out.println("The number of nodes is: " + tempTree.getNumNodes());
		
		tempTree.toDataArrays();
		System.out.println("The values are: " + Arrays.toString(tempTree.valuesArray));
		System.out.println("The indices are: " + Arrays.toString(tempTree.indicesArray));
		
		tempTree.toDataArraysObjectQueue();
		System.out.println("only object queue.");
		System.out.println("The values are: " + Arrays.toString(tempTree.valuesArray));
		System.out.println("The indices are: " + Arrays.toString(tempTree.indicesArray));
		
		char[] tempCharArray = {'A', 'B', 'C', 'D', 'E', 'F'};
		int[] tempIndicesArray = {0, 1, 2, 4, 5, 12};
		BinaryCharTree tempTree2 = new BinaryCharTree(tempCharArray, tempIndicesArray);
		
		System.out.println("rnPreorder visit:");
		tempTree2.postOrderVisit();
		System.out.println("rnIn-order visit:");
		tempTree2.inOrderVisit();
		System.out.println("rnPost-order visit:");
		tempTree2.postOrderVisit();
	} // Of main

运行结果：