2021. Brightest Position on Street
A perfectly straight street is represented by a number line. The street has street lamp(s) on it and is represented by a 2D integer array lights. Each lights[i] = [positioni, rangei] indicates that there is a street lamp at position positioni that lights up the area from [positioni - rangei, positioni + rangei] (inclusive).
The brightness of a position p is defined as the number of street lamp that light up the position p.
Given lights, return the brightest position on the street. If there are multiple brightest positions, return the smallest one.
In English, we have a concept called root, which can be followed by some other word to form another longer word - let’s call this word successor. For example, when the root “an” is followed by the successor word “other”, we can form a new word “another”.
Given a dictionary consisting of many roots and a sentence consisting of words separated by spaces, replace all the successors in the sentence with the root forming it. If a successor can be replaced by more than one root, replace it with the root that has the shortest length.
Return the sentence after the replacement.
1911. Maximum Alternating Subsequence Sum
The alternating sum of a 0-indexed array is defined as the sum of the elements at even indices minus the sum of the elements at odd indices.
- For example, the alternating sum of [4,2,5,3] is (4 + 5) - (2 + 3) = 4.
Given an array nums, return the maximum alternating sum of any subsequence of nums (after reindexing the elements of the subsequence).
A subsequence of an array is a new array generated from the original array by deleting some elements (possibly none) without changing the remaining elements’ relative order. For example, [2,7,4] is a subsequence of [4,2,3,7,2,1,4] (the underlined elements), while [2,4,2] is not.
1846. Maximum Element After Decreasing and Rearranging
You are given an array of positive integers arr. Perform some operations (possibly none) on arr so that it satisfies these conditions:
- The value of the first element in arr must be 1.
- The absolute difference between any 2 adjacent elements must be less than or equal to 1. In other words, abs(arr[i] - arr[i - 1]) <= 1 for each i where 1 <= i < arr.length (0-indexed). abs(x) is the absolute value of x.
There are 2 types of operations that you can perform any number of times:
- Decrease the value of any element of arr to a smaller positive integer.
- Rearrange the elements of arr to be in any order.
Return the maximum possible value of an element in arr after performing the operations to satisfy the conditions.
2024. Maximize the Confusion of an Exam
A teacher is writing a test with n true/false questions, with ‘T’ denoting true and ‘F’ denoting false. He wants to confuse the students by maximizing the number of consecutive questions with the same answer (multiple trues or multiple falses in a row).
You are given a string answerKey, where answerKey[i] is the original answer to the ith question. In addition, you are given an integer k, the maximum number of times you may perform the following operation:
- Change the answer key for any question to ‘T’ or ‘F’ (i.e., set answerKey[i] to ‘T’ or ‘F’).
Return the maximum number of consecutive ‘T’s or ‘F’s in the answer key after performing the operation at most k times.