ui设计怎么收费,seo外链查询工具,郑州 做网站,做阿里巴巴网站 店铺装修免费吗提示#xff1a;文章写完后#xff0c;目录可以自动生成#xff0c;如何生成可参考右边的帮助文档 文章目录 前言一、力扣993. 二叉树的堂兄弟节点二、力扣1315. 祖父节点值为偶数的节点和三、力扣1448. 统计二叉树中好节点的数目四、力扣1469. 寻找所有的独生节点 前言 二叉… 提示文章写完后目录可以自动生成如何生成可参考右边的帮助文档 文章目录 前言一、力扣993. 二叉树的堂兄弟节点二、力扣1315. 祖父节点值为偶数的节点和三、力扣1448. 统计二叉树中好节点的数目四、力扣1469. 寻找所有的独生节点 前言 二叉树的递归分为「遍历」和「分解问题」两种思维模式这道题需要用到「遍历」的思维。
一、力扣993. 二叉树的堂兄弟节点
/*** Definition for a binary tree node.* public class TreeNode {* int val;* TreeNode left;* TreeNode right;* TreeNode() {}* TreeNode(int val) { this.val val; }* TreeNode(int val, TreeNode left, TreeNode right) {* this.val val;* this.left left;* this.right right;* }* }*/
class Solution {int depthX -1, depthY -1;boolean flag true;public boolean isCousins(TreeNode root, int x, int y) {fun(root,1,x,y);if(flag false){return false;}if(depthX depthY){return true;}return false;}public void fun(TreeNode root, int depth, int x, int y){if(root null){return ;}if(root.val x){depthX depth;}if(root.val y){depthY depth;}if(root.left ! null root.right ! null){if((root.left.val x || root.left.val y) (root.right.val x || root.right.val y)){flag false;}}fun(root.left,depth1,x,y);fun(root.right,depth1,x,y);}
}二、力扣1315. 祖父节点值为偶数的节点和
/*** Definition for a binary tree node.* public class TreeNode {* int val;* TreeNode left;* TreeNode right;* TreeNode() {}* TreeNode(int val) { this.val val; }* TreeNode(int val, TreeNode left, TreeNode right) {* this.val val;* this.left left;* this.right right;* }* }*/
class Solution {int sum 0;public int sumEvenGrandparent(TreeNode root) {fun(root, null, null);return sum;}public void fun(TreeNode root, TreeNode parent, TreeNode grandParent){if(root null){return;}if(grandParent ! null grandParent.val % 2 0){sum root.val;}fun(root.left, root, parent);fun(root.right, root, parent);}
}三、力扣1448. 统计二叉树中好节点的数目
/*** Definition for a binary tree node.* public class TreeNode {* int val;* TreeNode left;* TreeNode right;* TreeNode() {}* TreeNode(int val) { this.val val; }* TreeNode(int val, TreeNode left, TreeNode right) {* this.val val;* this.left left;* this.right right;* }* }*/
class Solution {int count 0;public int goodNodes(TreeNode root) {fun(root,Integer.MIN_VALUE);return count;}public void fun(TreeNode root, int preMax){if(root null){return;}if(root.val preMax){preMax root.val;count ;}fun(root.left, preMax);fun(root.right, preMax);}
}四、力扣1469. 寻找所有的独生节点
/*** Definition for a binary tree node.* public class TreeNode {* int val;* TreeNode left;* TreeNode right;* TreeNode() {}* TreeNode(int val) { this.val val; }* TreeNode(int val, TreeNode left, TreeNode right) {* this.val val;* this.left left;* this.right right;* }* }*/
class Solution {ListInteger res new ArrayList();public ListInteger getLonelyNodes(TreeNode root) {fun(root);return res;}public void fun(TreeNode root){if(root null){return;}if(root.left null root.right ! null){res.add(root.right.val);}if(root.left ! null root.right null){res.add(root.left.val);}fun(root.left);fun(root.right);}
}
