[LeetCode] Verify Preorder Sequence in Binary Search Tree

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.

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[LeetCode] Maximum Product After K Increments

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.

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[LeetCode] Shift 2D Grid

1260. Shift 2D Grid

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.

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[LeetCode] Maximum Total Beauty of the Gardens

2234. Maximum Total Beauty of the Gardens

Alice is a caretaker of n gardens and she wants to plant flowers to maximize the total beauty of all her gardens.

You are given a 0-indexed integer array flowers of size n, where flowers[i] is the number of flowers already planted in the ith garden. Flowers that are already planted cannot be removed. You are then given another integer newFlowers, which is the maximum number of flowers that Alice can additionally plant. You are also given the integers target, full, and partial.

A garden is considered complete if it has at least target flowers. The total beauty of the gardens is then determined as the sum of the following:

  • The number of complete gardens multiplied by full.
  • The minimum number of flowers in any of the incomplete gardens multiplied by partial. If there are no incomplete gardens, then this value will be 0.

Return the maximum total beauty that Alice can obtain after planting at most newFlowers flowers.

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[LeetCode] Minimum Number of Removals to Make Mountain Array

1671. Minimum Number of Removals to Make Mountain Array

You may recall that an array arr is a mountain array if and only if:

  • arr.length >= 3
  • There exists some index i (0-indexed) with 0 < i < arr.length - 1 such that:
  • arr[0] < arr[1] < … < arr[i - 1] < arr[i]
  • arr[i] > arr[i + 1] > … > arr[arr.length - 1]

Given an integer array nums​​​, return the minimum number of elements to remove to make nums​​​ a mountain array.

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[LeetCode] Partition to K Equal Sum Subsets

698. Partition to K Equal Sum Subsets

Given an integer array nums and an integer k, return true if it is possible to divide this array into k non-empty subsets whose sums are all equal.

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[LeetCode] Baseball Game

682. Baseball Game

You are keeping score for a baseball game with strange rules. The game consists of several rounds, where the scores of past rounds may affect future rounds’ scores.

At the beginning of the game, you start with an empty record. You are given a list of strings ops, where ops[i] is the ith operation you must apply to the record and is one of the following:

  1. An integer x - Record a new score of x.
  2. “+” - Record a new score that is the sum of the previous two scores. It is guaranteed there will always be two previous scores.
  3. “D” - Record a new score that is double the previous score. It is guaranteed there will always be a previous score.
  4. “C” - Invalidate the previous score, removing it from the record. It is guaranteed there will always be a previous score.

Return the sum of all the scores on the record.

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[LeetCode] K-th Smallest Prime Fraction

786. K-th Smallest Prime Fraction

You are given a sorted integer array arr containing 1 and prime numbers, where all the integers of arr are unique. You are also given an integer k.

For every i and j where 0 <= i < j < arr.length, we consider the fraction arr[i] / arr[j].

Return the kth smallest fraction considered. Return your answer as an array of integers of size 2, where answer[0] == arr[i] and answer[1] == arr[j].

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[LeetCode] Remove Duplicates From an Unsorted Linked List

1836. Remove Duplicates From an Unsorted Linked List

Given the head of a linked list, find all the values that appear more than once in the list and delete the nodes that have any of those values.

Return the linked list after the deletions.

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[LeetCode] Linked List Cycle II

142. Linked List Cycle II

Given the head of a linked list, return the node where the cycle begins. If there is no cycle, return null.

There is a cycle in a linked list if there is some node in the list that can be reached again by continuously following the next pointer. Internally, pos is used to denote the index of the node that tail’s next pointer is connected to (0-indexed). It is -1 if there is no cycle. Note that pos is not passed as a parameter.

Do not modify the linked list.

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