/*求二叉树中距离最远的两个点* 基本思路：* 递归计算两棵树的最大高度，设置一个全局变量，距离最远的两个节点element* 其中：在计算左子支，直接刷新上述全局变量，在计算右边子支时，设置两个临时Node变量，变量里的element用于* 保存右边子支的两个最远距离。根据比较两个距离的大小、其父节点所在的树三个的大小，来重新刷新全局变量。* 一个Trick~：在计算子支的最远距离的时候，因为要和其父节点所在的树比较大小，保存子支的最大距离的点数。 */public class MaxLenTree {public Node root;public int len = 0;public class Node {char element;int hight;Node left;Node right;public Node(char element, int hight, Node left, Node right) {this.element = element;this.hight = hight;this.left = left;this.right = right;}Node() {}}MaxLenTree() {/*        Node e = new Node('e', 0, null, null);Node d = new Node('d', 0, e, null);Node f = new Node('f', 0, null, null);Node c = new Node('c', 0, d, f);Node b = new Node('b', 0, c, null);Node a = new Node('A', 0, b, null);*/Node m = new Node('m', 0, null, null);Node n = new Node('n', 0, null, null);Node k = new Node('k', 0, m, n);Node l = new Node('l', 0, null, null);Node i = new Node('i', 0, null, null);Node j = new Node('j', 0, k, l);Node q = new Node('q', 0, null, null);Node p = new Node('P', 0, q, null);Node h = new Node('h', 0, p, null);Node d = new Node('d', 0, h, null);Node e = new Node('e', 0, i, j);Node b = new Node('B', 0, d, e);Node f = new Node('f', 0, null, null);Node g = new Node('g', 0, null, null);Node c = new Node('c', 0, f, g);Node a = new Node('A', 0, b, c);root = a;}public static void main(String[] args) {MaxLenTree mTree = new MaxLenTree();mTree.calculateHight();mTree.run();}public void run() {Node node = new Node();System.out.println(findMaxLen(this.root, node));System.out.println("maxNode left.element---" + maxNodeleft.element);System.out.println("maxNoderight.element---" + maxNoderight.element);}public Node maxNodeleft = new Node();public Node maxNoderight = new Node();public int findMaxLen(Node root, Node LongestChild) {System.out.println(LongestChild.element);if (root.left == null && root.right == null) {LongestChild.element = root.element;maxNodeleft.element = root.element;maxNoderight.element = root.element;return 0;}Node leftLongestChild = new Node();Node rightLogestChild = new Node();if (root.left == null || root.right == null) {if (root.right == null) {int a = findMaxLen(root.left, leftLongestChild);System.out.println(leftLongestChild.element);if (hight(root) > a) {LongestChild.element = leftLongestChild.element;this.maxNodeleft.element = leftLongestChild.element;this.maxNoderight.element = root.element;return hight(root);} else {LongestChild.element = leftLongestChild.element;return a;}} else {int a = findMaxLen(root.right, rightLogestChild);if (hight(root) > a) {LongestChild.element = rightLogestChild.element;this.maxNodeleft.element = root.element;this.maxNoderight.element = rightLogestChild.element;return hight(root);} else {LongestChild.element = rightLogestChild.element;return a;}}}int a = findMaxLen(root.left, leftLongestChild);Node rightNodetempLeft = new Node();rightNodetempLeft.element = maxNodeleft.element;Node rightNodetempRight = new Node();rightNodetempRight.element = maxNoderight.element;int b = findMaxLen(root.right, rightLogestChild);int c = Math.max(a, b);if (a > b) {maxNodeleft.element = rightNodetempLeft.element;maxNoderight.element = rightNodetempRight.element;}if (c == b) {LongestChild.element = rightLogestChild.element;} else {LongestChild.element = leftLongestChild.element;}int d = hight(root.left) + hight(root.right) + 2;if (c < d) {maxNodeleft.element = leftLongestChild.element;maxNoderight.element = rightLogestChild.element;}System.out.println(LongestChild.element);return Math.max(c, d);}public int hight(Node root) {if (root == null) {return -1;}return root.hight;}public void showTree(Node root) {if (root == null) {return;}System.out.println(root.element + "<----->" + root.hight);showTree(root.left);showTree(root.right);}public void calculateHight() {calculateHight(this.root);}public int calculateHight(Node root) {if (root == null) {return -1;}if (root.right == null && root.left == null) {root.hight = 0;return 0;}int temp = Math.max(calculateHight(root.left),calculateHight(root.right)) + 1;root.hight = temp;return temp;}}