108. Convert Sorted Array to Binary Search Tree
Given an integer array nums where the elements are sorted in ascending order, convert it to a height-balanced binary search tree.
A height-balanced binary tree is a binary tree in which the depth of the two subtrees of every node never differs by more than one.
449. Serialize and Deserialize BST
Serialization is converting a data structure or object into a sequence of bits so that it can be stored in a file or memory buffer, or transmitted across a network connection link to be reconstructed later in the same or another computer environment.
Design an algorithm to serialize and deserialize a binary search tree. There is no restriction on how your serialization/deserialization algorithm should work. You need to ensure that a binary search tree can be serialized to a string, and this string can be deserialized to the original tree structure.
The encoded string should be as compact as possible.
1439. Find the Kth Smallest Sum of a Matrix With Sorted Rows
You are given an m x n matrix mat that has its rows sorted in non-decreasing order and an integer k.
You are allowed to choose exactly one element from each row to form an array.
Return the kth smallest array sum among all possible arrays.
There is a hotel with n rooms. The rooms are represented by a 2D integer array rooms where rooms[i] = [roomIdi, sizei] denotes that there is a room with room number roomIdi and size equal to sizei. Each roomIdi is guaranteed to be unique.
You are also given k queries in a 2D array queries where queries[j] = [preferredj, minSizej]. The answer to the jth query is the room number id of a room such that:
- The room has a size of at least minSizej, and
- abs(id - preferredj) is minimized, where abs(x) is the absolute value of x.
If there is a tie in the absolute difference, then use the room with the smallest such id. If there is no such room, the answer is -1.
Return an array answer of length k where answer[j] contains the answer to the jth query.
Given the root of a binary tree, find the largest subtree, which is also a Binary Search Tree (BST), where the largest means subtree has the largest number of nodes.
A Binary Search Tree (BST) is a tree in which all the nodes follow the below-mentioned properties:
- The left subtree values are less than the value of their parent (root) node’s value.
- The right subtree values are greater than the value of their parent (root) node’s value.
Note: A subtree must include all of its descendants.
A tree rooted at node 0 is given as follows:
- The number of nodes is nodes;
- The value of the ith node is value[i];
- The parent of the ith node is parent[i].
Remove every subtree whose sum of values of nodes is zero.
Return the number of the remaining nodes in the tree.
1798. Maximum Number of Consecutive Values You Can Make
You are given an integer array coins of length n which represents the n coins that you own. The value of the ith coin is coins[i]. You can make some value x if you can choose some of your n coins such that their values sum up to x.
Return the maximum number of consecutive integer values that you can make with your coins starting from and including 0.
Note that you may have multiple coins of the same value.
255. Verify Preorder Sequence in Binary Search Tree
Given an array of unique integers preorder, return true if it is the correct preorder traversal sequence of a binary search tree.
2233. Maximum Product After K Increments
You are given an array of non-negative integers nums and an integer k. In one operation, you may choose any element from nums and increment it by 1.
Return the maximum product of nums after at most k operations. Since the answer may be very large, return it modulo 109 + 7.
Given a 2D grid of size m x n and an integer k. You need to shift the grid k times.
In one shift operation:
- Element at grid[i][j] moves to grid[i][j + 1].
- Element at grid[i][n - 1] moves to grid[i + 1][0].
- Element at grid[m - 1][n - 1] moves to grid[0][0].
Return the 2D grid after applying shift operation k times.