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tamnd's digital brain — notes, problems, research
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The problem asks us to determine whether the absolute difference between every pair of adjacent digits in a given string s is at most 2. The input s is a string of digits, with a minimum length of 2 and a maximum of 100.
The problem asks us to determine the minimum cost to purchase apples starting from each shop, taking into account two types of costs: the local price of apples at each shop and the transportation costs along roads connecting the shops.
The problem gives an integer array nums and allows an operation that can reduce values under a divisibility condition. Specifically, you may choose two indices a and b such that nums[a] % nums[b] == 0, and then replace nums[a] with nums[b].
The problem asks us to construct a new array by concatenating an input array with its reversed version. Given an integer array nums of length n, we must return a new array ans of length 2 n. The first n elements of ans are exactly the same as nums, preserving order.
The problem gives an integer array nums of length n and an integer k. For every index i, we split the array into two overlapping parts: - The prefix nums[0..i] - The suffix nums[i..
This problem defines a process that repeatedly creates new 3D points from existing points. We begin with the given list points, which forms generation 0.
The circuit in Fig.
This problem asks us to simulate a simple scoring system while processing a sequence of event strings from left to right. We are given an array called events, where each element represents one event.
We are asked to determine if a specific sequence of partial sorts can guarantee that any array of length $n$ will be fully sorted at the end. The input specifies $n$, the size of the array, and $k$, the number of sorting steps Andrea performs.
The problem asks us to maximize the number of fixed points in an array after performing deletions. A fixed point is an index i such that nums[i] == i.
We are given a strictly increasing array nums. Each position represents an index in the array, and we want to move between indices as cheaply as possible. For every index x, a special neighbor called closest(x) is defined.
The problem gives us a single integer n. We first construct another integer r by reversing the digits of n. For example: - If n = 13, then r = 31 - If n = 10, then r = 1 - If n = 120, then r = 21 Once we have both numbers, we consider the inclusive range between them.
The problem gives us an integer array nums of length n. For every index i, we must determine how many indices to its right contain a number with the opposite parity. Parity refers to whether a number is even or odd: - Even numbers have a remainder of 0 when divided by 2.
Each athlete is described by five rankings, one ranking from each past marathon. Smaller values are better because a rank of 1 means first place. For two athletes x and y, we say that x is superior to y if x has a better rank in at least three of the five marathons.
We are given an array nums. In a single operation, we choose any contiguous subarray and increase every element in that subarray by the same positive integer value x. The cost of an operation is exactly the chosen value x.
The solution does address the correct exercise and correctly identifies that the task is to generalize Algorithm S by handling the case when subtraction is performed without knowing which operand is larger.
The problem requires us to reorder the vowels in a given string s based on their frequency, while keeping all consonants in their original positions. Specifically, the vowels must appear in non-increasing order of frequency.
The solution does address the correct exercise and correctly identifies that the task is to generalize Algorithm S by handling the case when subtraction is performed without knowing which operand is larger.
The problem provides a strictly increasing integer array nums and a list of queries, each consisting of [li, ri, ki]. For each query, we consider the subarray nums[li..ri] and remove all elements of this subarray from the infinite sequence of positive even integers.
We have a set of distinct integers $a1,dots,an$, each lying in the range $[0,2^k)$. For every mask $x$, we XOR every array element with $x$, producing the set $${a1oplus x,dots,anoplus x}.$$ Among all pairs in that transformed set, we want the smallest absolute difference.
The problem gives us a bitonic array nums, meaning an array that first strictly increases to a single peak element and then strictly decreases. The task is to split this array into two overlapping parts: 1.
The solution does address the correct exercise and correctly identifies that the task is to generalize Algorithm S by handling the case when subtraction is performed without knowing which operand is larger.
The problem is asking us to determine whether a given integer n is valid with respect to a digit x based on two conditions. First, n must contain at least one occurrence of the digit x. Second, n must not start with digit x.
A luminous object is placed on the optical axis of a thin converging lens $\text{Л}_1$ with focal length $F$.
The solution does address the correct exercise and correctly identifies that the task is to generalize Algorithm S by handling the case when subtraction is performed without knowing which operand is larger.
The problem asks us to simulate a multi-source flood fill on an n x m grid. Each element of the sources array represents a starting point with a specific color, and all other cells start uncolored, represented as 0.
The problem asks us to find the smallest index i in an integer array nums such that the instability score at that index is less than or equal to a given integer k. The instability score is defined as the difference between the maximum of the prefix nums[0..
The solution does address the correct exercise and correctly identifies that the task is to generalize Algorithm S by handling the case when subtraction is performed without knowing which operand is larger.
We are simulating a penalty shootout between two football teams, each taking alternating kicks up to five each, for a total of ten kicks. Each kick either succeeds (scores a goal), fails, or is unknown.
A wire spiral is connected to an ideal constant-voltage mains source with voltage $V$.
We are given a binary string s containing only '0' and '1'. A substring is considered balanced when it contains exactly the same number of zeros and ones. Before choosing the substring, we are allowed to perform at most one swap between any two positions in the entire string.
The problem asks us to calculate the degree of each vertex in an undirected graph represented by an adjacency matrix. The input is a 2D integer array matrix of size n x n, where matrix[i][j] = 1 indicates an edge between vertices i and j, and matrix[i][j] = 0 indicates no edge.
The problem presents two integer arrays nums1 and nums0, each of size n. Each index i represents a binary segment consisting of a number of '1' bits followed by a number of '0' bits.
The problem asks us to count how many times a specific decimal digit appears when writing out every number in the array. We are given an integer array nums and a single digit between 0 and 9.
This problem asks us to determine the current state of a traffic signal based on an integer timer that represents the remaining seconds for the signal.
The problem asks us to transform an integer array nums into an alternating prime array, where numbers at even indices are prime and numbers at odd indices are non-prime.
We are given a circular array nums. An index is considered a peak if its value is strictly greater than both of its neighbors. Because the array is circular, the first and last elements are adjacent. For example, the neighbors of index 0 are nums[n - 1] and nums[1].
This problem describes a dynamic process of building an undirected graph with weighted edges where the weights are binary, either 0 or 1. You start with n isolated nodes labeled from 0 to n-1.
The problem asks us to find all integers k that divide the length of the input array nums and for which the array can be sorted into non-decreasing order using a very specific operation.
Exercise 4.3.1.9 asks for a generalization of Algorithm A to add two -place numbers in a mixed-radix system with bases from right to left. Algorithm A in TAOCP §4.3.1 describes standard addition with carry propagation in a single-radix positional system.
The problem asks us to count the number of contiguous subarrays of a given integer array nums that contain exactly one peak, where a peak is defined as an element nums[i] that is strictly greater than both its immediate neighbors nums[i-1] and nums[i+1].
The problem presents a straightforward search scenario. You are given an array capacity where each element represents the storage capacity of a box. You are also given an integer itemSize, representing the size of an item you want to store.
This problem asks us to count subarrays of a given integer array nums such that each subarray contains exactly k distinct integers, and each distinct integer in the subarray appears at least m times.
This problem asks us to determine the minimum positive integer k such that, after repeatedly subtracting k from each element of the array nums, the total number of operations needed to reduce every element to non-positive is at most k^2.
The problem requires identifying special nodes in a tree based on distances to three distinct target nodes, x, y, and z.
Exercise 4.3.1.9 asks for a generalization of Algorithm A to add two -place numbers in a mixed-radix system with bases from right to left. Algorithm A in TAOCP §4.3.1 describes standard addition with carry propagation in a single-radix positional system.
We are given a tree with $n$ nodes, which is a connected acyclic graph, and we need to construct sequences by repeatedly erasing nodes.
We are given two arrays, nums and target, of equal length. The array nums represents the current state, while target represents the desired final state. In one operation, we choose a value x. Then we locate every maximal contiguous segment whose current value is exactly x.
Exercise 4.3.1.9 asks for a generalization of Algorithm A to add two -place numbers in a mixed-radix system with bases from right to left. Algorithm A in TAOCP §4.3.1 describes standard addition with carry propagation in a single-radix positional system.
This problem asks us to identify the "best reachable tower" from a given center location within a specified Manhattan distance radius. Each tower has a coordinate (xi, yi) and a quality factor qi.
We are given an n × m grid where each cell is either available ('.') or blocked (''). A route starts from any available cell in the bottom row and must eventually end in the top row. During the route, every visited cell must be available. The movement rules are unusual: 1.
Exercise 4.3.1.9 asks for a generalization of Algorithm A to add two -place numbers in a mixed-radix system with bases from right to left. Algorithm A in TAOCP §4.3.1 describes standard addition with carry propagation in a single-radix positional system.
We are asked to design an algorithm that adds two numbers digit by digit from most significant to least significant, producing each output digit only when it cannot possibly be affected by future carries. Once an output digit is committed, it may never be revised.
We are given a string s that contains only the characters '1' and '2'. We are allowed to delete any number of characters while preserving the relative order of the remaining characters. In other words, we may choose any subsequence of the original string.
The prompts table records every prompt submitted by a user to an AI system. Each row contains a userid, the prompt text itself, and the number of tokens consumed by that prompt.
We are given an array of positive integers. For every subarray that contains at least two elements, we compute the product of its largest element and its smallest element. The task is to find the maximum such product among all possible subarrays.
The problem asks us to identify special nodes in a tree, which are nodes that serve as endpoints of any diameter path. A tree is an acyclic connected graph, and its diameter is defined as the longest simple path between any two nodes.
This problem asks us to modify an array nums so that for every index i, the element at nums[i] is not equal to the corresponding element at forbidden[i]. The only allowed operation is swapping any two distinct elements of nums.
We are given a mutable binary string consisting only of 'A' and 'B'. There are two kinds of queries: - [1, j] flips the character at position j. If it was 'A', it becomes 'B', and vice versa. This permanently changes the string and affects all future queries.
The problem gives us a positive integer n and asks us to compute its mirror distance. The mirror distance is defined as: where reverse(n) is the integer obtained by reversing the decimal digits of n, and |x| denotes the absolute value.
We are maintaining an undirected graph that grows edge by edge. Every edge has a binary weight, either 0 or 1. After each insertion request, we must decide whether adding that edge keeps a certain global property valid.
Exercise 4.3.1.7 asks for the average number of times the algorithm of Exercise 5 finds that a carry propagates through exactly digits of the partial answer, for , under the assumption that both inputs are independent and uniformly distributed integers in .
We are given two values: - n, which determines the numbers 1, 2, ..., n - target, which is the required sum of the final array We must construct an array of length n whose absolute values are exactly the numbers 1 through n, each used once.
We are given a 2-row grid of coins with m columns. Alice and Bob both start at the top-left corner (1,1) and want to reach the bottom-right (2,m) using only moves to the right or down. Alice moves first and collects all coins along her path.
The problem asks us to consider all integers from 1 up to a given number n. For each integer, we are required to write down a transformed version of that number in which all zeros are removed. For example, 102 would become 12, and 500 would become 5.
The problem gives us an integer array nums and asks us to find three distinct indices (i, j, k) such that all three positions contain the same value: Such a triple is called a good tuple.
The problem is asking us to manipulate a string s of length n in order to produce the lexicographically smallest possible string after exactly one operation.
This problem asks us to maximize the product of any three distinct elements in an array, given that we are allowed to replace exactly one element in the array with any integer from -10^5 to 10^5. The input is an integer array nums of length at least 3 and at most 10^5.
The problem asks us to find the longest contiguous subarray of an integer array nums such that the number of distinct even numbers in the subarray is equal to the number of distinct odd numbers.
The problem is asking us to find the length of the longest substring of a given string s where all distinct characters in that substring appear the same number of times.
This problem asks us to compute the alternating sum of an integer array nums. The alternating sum is calculated by taking the sum of elements at even indices (0, 2, 4, ...) and subtracting the sum of elements at odd indices (1, 3, 5, ...).
The crash is now purely an input-format mismatch, and it already reveals exactly where the implementation diverges from the actual problem.
Exercise 4.3.1.7 asks for the average number of times the algorithm of Exercise 5 finds that a carry propagates through exactly digits of the partial answer, for , under the assumption that both inputs are independent and uniformly distributed integers in .
The problem asks us to find the maximum product of two distinct elements in an array of integers, under the constraint that their binary representations do not share any set bits.
The problem asks us to split a positive integer n into exactly k positive integers such that the product of these integers equals n. Among all possible splits, we are required to find one in which the maximum difference between any two numbers is minimized.
We are given an integer array nums and an integer k. The goal is to determine whether all elements of the array can be partitioned into one or more groups such that every group satisfies two conditions: 1. Each group contains exactly k elements. 2.
This problem asks us to count the number of perfect pairs in an integer array nums. A pair (i, j) is perfect if i < j and the elements at these indices satisfy two conditions: the minimum of |a - b| and |a + b| is less than or equal to the smaller absolute value of the two…
We interpret the task as follows. Two nonnegative integers are given in radix , each represented as a sequence of digits. The digits are not processed in the standard right-to-left carry propagation.
The problem provides a permutation array nums of length n, meaning it contains each integer from 0 to n-1 exactly once, in some arbitrary order.
The solution partially addresses the exercise, but it does not fully satisfy what was asked. The exercise is not asking for modern algorithms that resemble the work of Sun Tsï, al-Khwārizmī, al-Uqlidisī, Fibonacci, and Recorde.
The problem asks us to efficiently handle queries on an array nums involving a special property called the popcount-depth.
We are given an array nums whose length is always divisible by 3. The array must be emptied by repeatedly selecting exactly three elements. For each selected triple, we compute its median, add that median to our answer, and remove all three elements from the array.
This problem is essentially about navigating an array using two types of moves: adjacent steps and prime-based teleportation. You start at the first index and want to reach the last index in the minimum number of moves.
No. The proposed solution does not answer Exercise 4.3.1.1 at all. Exercise 4.3.1.1 asks the reader to study the early history of classical arithmetic algorithms by consulting historical sources (e.g.
The problem asks us to count the number of horizontal trapezoids that can be formed from a set of points in 2D Cartesian space.
The problem asks us to minimize the maximum cost among components in a connected undirected graph after removing edges. Each edge has a weight, and the cost of a connected component is the largest weight of any edge in that component.
We are given an undirected graph with n vertices and a list of edges. Each edge has a removal time timei. The graph evolves over time. At time t, every edge whose removal time satisfies timei <= t has already been removed. All remaining edges are those with timei t.
We are given a token placed at position $n$ on a vertical line of cells labeled from $1$ at the top to $n$ at the bottom. The goal is to count how many distinct sequences of moves can bring the token from $n$ down to $1$. From a position $x 1$, two types of moves are allowed.
This problem asks us to analyze fuel efficiency trends for drivers across two different periods of the year. We are given two tables: - drivers, which stores each driver's identifier and name.
The problem gives us a single integer n and asks us to construct a string from two different number system conversions.
Program B is designed to perform a sequence of numerical calculations using the X-register of a hypothetical or HP-style RPN calculator. In such machines, the X-register holds the current number on the stack.
We are given a token placed at position on a vertical line of cells labeled from at the top to at the bottom. The goal is to count how many distinct sequences of moves can bring the token from down to . From a position , two types of moves are allowed.
The problem requires transforming a given array of distinct integers into an arrangement where the parity of adjacent elements alternates - that is, an even number must always be next to an odd number, and vice versa.
This problem asks us to count the number of special triplets in an integer array nums. A special triplet (i, j, k) must satisfy three conditions: the indices are strictly increasing 0 <= i < j < k < n, nums[i] is exactly double nums[j], and nums[k] is also exactly double nums[j].
This problem asks us to maximize profit from buying and selling stocks under a hierarchical discount structure. Each employee can buy a stock today at a present price and sell it tomorrow at a future price.
We are given an array of integers and allowed to perform a repeated operation: choose any contiguous subarray and replace each element in it with the bitwise AND of itself and its symmetric counterpart relative to the interval.
Here is a complete, detailed technical solution guide following your exact formatting rules. This problem asks us to handle dynamic array updates and, after each update, find the maximum sum of distinct prime counts across any valid split of the array.
The problem asks us to sort an array of distinct positive integers not by their natural numeric value, but by the sum of their digits. If two numbers share the same digit sum, the smaller number must come first.
We are given a grid representing a classroom. A student starts at the cell marked 'S' and must collect every litter cell marked 'L'. Movement is allowed only in the four cardinal directions, and moving one cell costs exactly one unit of energy.
This problem asks us to analyze sales data and determine the most popular product category for each season based on the total quantity sold.