翻转二叉树

package 二叉树.反转二叉树;import 二叉树.TreeNode;import java.util.ArrayList;
import java.util.LinkedList;
import java.util.List;
import java.util.Queue;public class Solution {public static void main(String[] args) {TreeNode root=new TreeNode(1);TreeNode node2=new TreeNode(2);TreeNode node3=new TreeNode(3);TreeNode node4=new TreeNode(4);TreeNode node5=new TreeNode(5);TreeNode node6=new TreeNode(6);TreeNode node7=new TreeNode(7);TreeNode node8=new TreeNode(8);root.setLeft(node2);root.setRight(node3);node2.setLeft(node4);node2.setRight(node5);node3.setRight(node6);node5.setLeft(node7);node5.setRight(node8);System.out.println(root);List integers=new ArrayList<>();inorderTraversal(root,integers);System.out.println(integers);List newRootIntegers=new ArrayList<>();TreeNode newRoot=invertTree(root);inorderTraversal(newRoot,newRootIntegers);System.out.println(newRootIntegers);}public static TreeNode invertTree(TreeNode root) {TreeNode node=null;if (root==null){return null;}invertTree(root.left);invertTree(root.right);node=root.right;root.right=root.left;root.left=node;return root;}public static void inorderTraversal(TreeNode root,List integers ){if (root==null){return;}inorderTraversal(root.left,integers);integers.add(root.val);inorderTraversal(root.right,integers);}}

 二叉树最大深度

 力扣

package 二叉树.最大深度;import 二叉树.TreeNode;import java.util.ArrayList;
import java.util.LinkedList;
import java.util.List;
import java.util.Queue;public class Solution {public static void main(String[] args) {TreeNode root=new TreeNode(1);TreeNode node2=new TreeNode(2);TreeNode node3=new TreeNode(3);TreeNode node4=new TreeNode(4);TreeNode node5=new TreeNode(5);TreeNode node6=new TreeNode(6);TreeNode node7=new TreeNode(7);TreeNode node8=new TreeNode(8);root.setLeft(node2);root.setRight(node3);node2.setLeft(node4);node2.setRight(node5);node3.setRight(node6);node5.setLeft(node7);node5.setRight(node8);
//        int max = maxDepth(root);int max = maxDepthMethodForLoop(root);System.out.println("----------二叉树最大深度为------"+max);}public static int maxDepth(TreeNode root) {int deep=0;if(root==null){return 0;}else{return Math.max( maxDepth(root.right), maxDepth(root.left))+1;}}public static int maxDepthMethodForLoop(TreeNode root) {int deep=0;Queue queue=new LinkedList<>();queue.offer(root);while (!queue.isEmpty()){int size=queue.size();while (size>0){TreeNode treeNode=queue.poll();if(treeNode.left!=null){queue.offer(treeNode.left);}if(treeNode.right!=null){queue.offer(treeNode.right);}System.out.println(queue);System.out.println(queue.size());System.out.println(size);size--;}deep++;}return deep;}}

平衡二叉树

力扣​​​​​​​

package 二叉树.平衡二叉树;import 二叉树.TreeNode;import java.util.ArrayList;
import java.util.List;public class Solution {public static void main(String[] args) {TreeNode root=new TreeNode(1);TreeNode node2=new TreeNode(2);TreeNode node3=new TreeNode(3);TreeNode node4=new TreeNode(4);TreeNode node5=new TreeNode(5);TreeNode node6=new TreeNode(6);TreeNode node7=new TreeNode(7);TreeNode node8=new TreeNode(8);root.setLeft(node2);root.setRight(node3);node2.setLeft(node4);node2.setRight(node5);node3.setRight(node6);node5.setLeft(node7);node5.setRight(node8);int balanced = isBalanced(root);System.out.println(balanced);}public static int isBalanced(TreeNode root) {if(root==null){return 0;}int left=isBalanced(root.left);int right=isBalanced(root.right);System.out.println(left);System.out.println(right);if(left==-1||right==-1||Math.abs(left-right)>1){return -1;}return Math.max(left,right)+1;}}