1.判断两个数是否相同
题目链接：. - 力扣（LeetCode）
public boolean isSameTree(TreeNode p, TreeNode q) {if(p==null && q!=null || q==null && p!=null){return false;}if(p==null && q==null){return true;}if(q.val!=p.val){return false;}return isSameTree(p.left,q.left) && isSameTree(p.right,q.right);}2.另一颗的子树
题目链接：. - 力扣（LeetCode）
class Solution {public boolean isSubtree(TreeNode root, TreeNode subRoot) {if(root==null){return false;}if(isSameTree(root,subRoot)){return true;}if(isSubtree(root.left,subRoot)){;return true;}if(isSubtree(root.right,subRoot)){;return true;}return false;}public boolean isSameTree(TreeNode p, TreeNode q) {if(p==null && q!=null || q==null && p!=null){return false;}if(p==null && q==null){return true;}if(q.val!=p.val){return false;}return isSameTree(p.left,q.left) && isSameTree(p.right,q.right);}
}3.翻转二叉树
题目链接：. - 力扣（LeetCode）
public TreeNode invertTree(TreeNode root) {if(root==null){return null;}TreeNode tem=null;tem=root.left;root.left=root.right;root.right=tem;invertTree(root.left);invertTree(root.right);return root;}4.对称二叉树
题目链接：. - 力扣（LeetCode）
class Solution {public boolean isSymmetric(TreeNode root) {if(root==null){return true;}return isChild(root.left,root.right);}public boolean isChild(TreeNode a1,TreeNode a2){if(a1==null && a2!=null || a1!=null && a2==null){return false;}if(a1==null && a2==null){return true;}if(a1.val!=a2.val ){return false;}return isChild(a1.left,a2.right)&&isChild(a1.right,a2.left);}5.平衡二叉树
题目链接：. - 力扣（LeetCode）
public int getHeight(TreeNode root){if(root==null){return 0;}int leftHeight=getHeight(root.left);if(leftHeight<0){return -1;}int rightHeight=getHeight(root.right);if(rightHeight>=0 && Math.abs(leftHeight-rightHeight)<=1){return Math.max(leftHeight,rightHeight)+1;}else {return -1;}}6.二叉树的遍历
题目链接：二叉树遍历_牛客题霸_牛客网
public static void main(String[] args) {Scanner in = new Scanner(System.in);// 注意 hasNext 和 hasNextLine 的区别while (in.hasNextInt()) { // 注意 while 处理多个 caseString str=in.nextLine();TreeNode root=creatTree(str);inorderTree(root);}}public static int i=0;public static TreeNode creatTree(String str){TreeNode root=null;if(str.charAt(i)!='#'){root=new TreeNode(str.charAt(i));i++;root.left=creatTree(str);root.right=creatTree(str);}else{i++;}return root;}public static void inorderTree(TreeNode root){if(root==null){return ;}inorderTree(root.left);System.out.print(root.val+" ");inorderTree(root.right);}7.二叉树的分层遍历
题目链接：. - 力扣（LeetCode）
class Solution {public List<List<Integer>> levelOrder(TreeNode root) {List<List<Integer>> ret=new ArrayList<>();if(root==null){return ret;}Queue<TreeNode> queue=new LinkedList<>();queue.offer(root);while(!queue.empty()){int size=queue.size();List<Character> list=new List<>();while(size!=0){TreeNode<Character> cur=queue.poll();list.add(cur.val);if(cur.left!=null){queue.offer(cur.left);}if(cur.right!=null){queue.offer(cur.right);}size--;}ret.add(list);} return ret;}
}希望能对大家有所帮助！！！！！！
