package com.binaryTree;

import org.omg.CORBA.MARSHAL;

import java.util.HashMap;
import java.util.LinkedList;
import java.util.Map;
import java.util.Queue;

// 求二叉树最宽的层有多少个节点(即二叉树的最大宽度)
public class TreeMaxWidth {
 public static class Node {
 public int value;
 public Node left;
 public Node right;

 public Node(int data) {
 this.value = data;
 }
 }
 public static int maxWidth1(Node head){
 if (head == null){
 return 0;
 }
 Node curEnd = head; // 记录当前层的最后节点
 Node nextEnd = null; // 记录下一层的最后节点
 int count = 0; // count记录当前层的节点个数(宽度),因为由前面if判断知道,head不为null,故当前层的节点数为1
 int max = 0; // 最后返回的最大宽度
 Queue<Node> queue = new LinkedList<>();
 queue.add(head);
 while (!queue.isEmpty()){
 Node cur = queue.poll();
 count++; // 每从queue中poll节点但 cur!=curEnd(没遍历当前层的最后节点时),当前层的节点数count+1
 if (cur.left != null){
 queue.add(cur.left);
 nextEnd = cur.left;
 }
 if (cur.right != null){
 queue.add(cur.right);
 nextEnd = cur.right;
 }

 if (cur == curEnd){
 max = Math.max(max,count);
 curEnd = nextEnd;
 count = 0;
 }
 }
 return max;
 }

 public static int maxWidth2(Node head){
 if (head == null){
 return 0;
 }
 Queue<Node> queue = new LinkedList<>();
 queue.add(head);
 int curLevel = 1; // 当前统计宽度的层数
 Map<Node,Integer> map = new HashMap<>();
 map.put(head,1);

 int count = 0;
 int max = 0;
 while (!queue.isEmpty()){
 Node cur = queue.poll();
 int nodeLevel = map.get(cur); // cur节点所在层数
 if (cur.left != null){
 map.put(cur.left,nodeLevel+1);
 queue.add(cur.left);
 }
 if (cur.right != null){
 map.put(cur.right,nodeLevel+1);
 queue.add(cur.right);
 }
 if (curLevel == nodeLevel){ // 当前统计宽度的层数与cur节点所在层数相等,节点数count +1
 count++;
 }else {
 curLevel++;
 max = Math.max(max,count);
 count = 1;
 }
 }
 max = Math.max(max,count);
 return max;
 }

 // for test
 public static Node generateRandomBST(int maxLevel, int maxValue) {
 return generate(1, maxLevel, maxValue);
 }

 // for test
 // level为当前创建节点的层数
 public static Node generate(int level, int maxLevel, int maxValue) {
 if (level > maxLevel || Math.random() < 0.5) {
 return null;
 }
 Node head = new Node((int) (Math.random() * maxValue));
 head.left = generate(level + 1, maxLevel, maxValue);
 head.right = generate(level + 1, maxLevel, maxValue);
 return head;
 }

 public static void main(String[] args) {
 int maxLevel = 10;
 int maxValue = 100;
 int testTimes = 1000000;
 System.out.println("test start:");
 for (int i = 0; i < testTimes; i++) {
 Node head = generateRandomBST(maxLevel, maxValue);
 if (maxWidth1(head) != maxWidth2(head)) {
 System.out.println("Oops!");
 }
 }
 System.out.println("finish!");
 }

}