建设工程招标网站,怎么把网站扒下来,视频网站如何优化,自己制作视频的app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100. 相同的树二、力扣1367. 二叉树中的链表三、力扣105. 从前序与中序遍历序列构造二叉树四、力扣654. 最大二叉树 前言 最常见的#xff0c;二叉树的… 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100. 相同的树二、力扣1367. 二叉树中的链表三、力扣105. 从前序与中序遍历序列构造二叉树四、力扣654. 最大二叉树 前言 最常见的二叉树的列构造问题一般都会用到分解问题的思维模式。
一、力扣100. 相同的树
/*** 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 {public boolean isSameTree(TreeNode p, TreeNode q) {if(p null q null){return true;}if(p null || q null){return false;}if(p.val ! q.val){return false;}return isSameTree(p.left,q.left) isSameTree(p.right, q.right);}
}二、力扣1367. 二叉树中的链表
/*** Definition for singly-linked list.* public class ListNode {* int val;* ListNode next;* ListNode() {}* ListNode(int val) { this.val val; }* ListNode(int val, ListNode next) { this.val val; this.next next; }* }*/
/*** 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 {public boolean isSubPath(ListNode head, TreeNode root) {if(head null){return true;}if(root null){return false;}if(head.val root.val){if(fun(root,head)){return true;}}return isSubPath(head,root.left) || isSubPath(head,root.right);}public boolean fun(TreeNode root, ListNode head){if(head null){return true;}if(root null){return false;}if(root.val ! head.val){return false;}return fun(root.left, head.next) || fun(root.right, head.next);}
}三、力扣105. 从前序与中序遍历序列构造二叉树
/*** 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 {public TreeNode buildTree(int[] preorder, int[] inorder) {return fun(preorder,inorder, 0,preorder.length-1,0,inorder.length-1);}public TreeNode fun(int[] preorder, int[] inorder, int preLow,int preHigh, int inLow,int inHigh){if(preLow preHigh){return null;}TreeNode cur new TreeNode(preorder[preLow]);int index 0, len 0;for(int i inLow; i inHigh; i ){if(inorder[i] preorder[preLow]){index i;len index - inLow;break;}}cur.left fun(preorder,inorder,preLow1,preLowlen,inLow,index-1);cur.right fun(preorder,inorder,preLowlen1,preHigh,index1,inHigh);return cur;}
}四、力扣654. 最大二叉树
/*** 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 {public TreeNode constructMaximumBinaryTree(int[] nums) {return fun(nums,0, nums.length-1);}public TreeNode fun(int[] nums, int low, int high){if(low high){return null;}int index low;for(int i low; i high; i ){index nums[i] nums[index] ? i:index;}TreeNode cur new TreeNode(nums[index]);cur.left fun(nums,low, index-1);cur.right fun(nums,index1,high);return cur;}
}
