classSolution {public:boolisValidBST(TreeNode*root) { TreeNode*pre =NULL;returninorder(root, pre); }boolinorder(TreeNode* node, TreeNode*&pre) {if(!node)returntrue;boolres = inorder(node->left, pre);if(!res)returnfalse;if(pre) {if(node->val <= pre->val)returnfalse; } pre=nod...
Given a binary tree, determine if it is a valid binary search tree (BST).Assume a BST is defined as follows: The left subtree of a node contains only nodes with keys less than the node's key. The right subtree of a node contains only nodes with keys greater than the node's key. ...
The right subtree of a node contains only nodes with keys greater than the node's key. Both the left and right subtrees must also be binary search trees. Example 1: Input: 2 / \ 1 3 Output: true Example 2: 5 / \ 1 4 / \ 3 6 Output: false Explanation: The input is: [5,1...
Explanation: The root node's value is 5 but its right child's value is 4. 1. 2. 3. 4. 5. 6. 7. 8. 9. 题解: 中序遍历看序列是否有序即可。 classSolution{ public: voidvisitTree(TreeNode*root,vector<int>&res) { if(root!=NULL) { visitTree(root->left,res); res.push_back(r...
Explanation: This is not the only correct answer, [3,1,4,null,2,null,null] is also correct. 1. 2. 3. Constraints: The number of nodes in the tree is between1 and10^4. The tree nodes will have distinct values between1 and...
95. Unique Binary Search Trees II Given an integer n, generate all structurally unique BST's (binary search trees) that store values 1 ... n. Example: Input:3Output:[ [1,null,3,2],[3,2,null,1],[3,1,null,null,2], [2,1,3],[1,null,2,null,3]]Explanation:The above output ...
The explanation above provides a rough description of the algorithm. For the implementation details, we'd need to be more precise.We will maintain a pair L<R such that AL≤k<AR . Meaning that the active search interval is [L,R) . We use half-interval ...
User.search You would do: User.searchlogic Under the hood¶↑ Before I use a library in my application I like to glance at the source and try to at least understand the basics of how it works. If you are like me, a nice little explanation from the author is always helpful: ...
Given a binary tree, return all paths from the root to leaves.For example, given the tree1 / \ 2 3 / \ 4 5 it should return [[1, 2], [1, 3, 4], [1, 3, 5]].AnalysisThe phrasing of the answer seems to assume the use of Python. My program creates a binary search tree ...
Both the left and right subtrees must also be binary search trees. Example 1: Input: 2 / \ 1 3 Output: true Example 2: 5 / \ 1 4 / \ 3 6 Output: false Explanation: The input is: [5,1,4,null,null,3,6]. The root node's value ...