网站开发工作经验简历,php网站开发程序,电脑编程教学入门教程,网站备案 教程一、LeetCode 654 最大二叉树
题目链接#xff1a;654.最大二叉树https://leetcode.cn/problems/maximum-binary-tree/ 思路#xff1a;坚持左开右闭原则#xff0c;递归划分数组元素生成左右子树。 class Solution {public TreeNode constructMaximumBinaryTree(int[] num…一、LeetCode 654 最大二叉树
题目链接654.最大二叉树https://leetcode.cn/problems/maximum-binary-tree/ 思路坚持左开右闭原则递归划分数组元素生成左右子树。 class Solution {public TreeNode constructMaximumBinaryTree(int[] nums) {return travel(nums,0,nums.length);}//坚持左闭右开public TreeNode travel(int[] nums, int left, int right){//空数组返回空值if(right - left 1){return null;}//数组只有一个元素为叶子节点if(right - left 1){return new TreeNode(nums[left]);}//找到数组中的最大元素及其下标int maxIndex left;int maxValue nums[left];for(int i left1; i right; i){if(nums[i] maxValue){maxIndex i;maxValue nums[i];}}TreeNode node new TreeNode(nums[maxIndex]);//划分数组生成左右子树node.left travel(nums,left,maxIndex);node.right travel(nums,maxIndex1,right);return node;}
}
/*** 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;* }* }*/ 二、LeetCode 617 合并二叉树
题目链接617.合并二叉树https://leetcode.cn/problems/merge-two-binary-trees/submissions/502582353/ 思路前序递归遍历处理空节点情况~ class Solution {public TreeNode mergeTrees(TreeNode root1, TreeNode root2) {//处理root1和root2节点为空的情况if(root1 null root2 null){return null;}if(root1 ! null root2 null){return root1;}if(root1 null root2 ! null){return root2;}//建立新节点TreeNode root new TreeNode(root1.val root2.val);//中、左、右递归遍历root.left mergeTrees(root1.left,root2.left);root.right mergeTrees(root1.right,root2.right);return root;}
}
/*** 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;* }* }*/
三、LeetCode 700 二叉树中的搜索
题目链接700.二叉树中的搜索https://leetcode.cn/problems/search-in-a-binary-search-tree/ 思路前序遍历非左即右~ class Solution {public TreeNode searchBST(TreeNode root, int val) {//找到空节点说明该路径上没有符合条件的节点if(root null){return null;}//找到符合条件的节点if(root.val val){return root;}//前序遍历 中、左、右TreeNode left searchBST(root.left,val);TreeNode right searchBST(root.right,val);//非左即右return left null ? right : left;}
}
/*** 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;* }* }*/
四、小结 静心刷题ovo
