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question:# Problem Description You are developing a company website that sells books online. One of the features is to recommend books to customers based on their browsing history. The browsing history is stored as a list of book IDs. Each time a customer visits a book page, the book ID is added to the browsing history. Your task is to write a function that takes the browsing history of a customer and returns the ID of the book that has been visited the most. If there is a tie (i.e., multiple books have been visited the same maximum number of times), return the smallest book ID. # Function Signature ```python def most_visited_book(browsing_history: list) -> int: ``` # Input * browsing_history (list): A list of integers representing the book IDs in the order they were visited. The list will have at least one element. # Output * (int): The book ID that has been visited the most. If there is a tie, return the smallest book ID. # Example ```python browsing_history = [1, 2, 1, 2, 3, 1, 3, 1, 2, 2] most_visited_book(browsing_history) ``` This should return: ```output 2 ``` # Explanation - The book with ID 1 is visited 4 times. - The book with ID 2 is visited 4 times. - The book with ID 3 is visited 2 times. - Since there is a tie between book ID 1 and book ID 2, the function should return the smallest book ID, which is 1.
answer:def most_visited_book(browsing_history: list) -> int: Returns the ID of the most visited book. If multiple books have been visited the same maximum number of times, returns the smallest book ID. from collections import Counter # Count the occurrences of each book ID book_count = Counter(browsing_history) # Find the maximum visit count max_visits = max(book_count.values()) # Filter the book IDs that have the maximum visit count most_visited_books = [book_id for book_id, count in book_count.items() if count == max_visits] # Return the smallest book ID among those return min(most_visited_books)
question:You are provided with a sequence of integers representing the prices of a stock on different days. Your task is to find the maximum profit you can achieve from making at most two transactions. A transaction is defined as buying and then selling one unit of stock. The order in which you perform the buy and sell operations matters, and you must buy the stock before you can sell it. You must also complete one transaction before starting another. Write a function `max_profit` that takes in a list of integers `prices` and returns an integer representing the maximum profit obtainable from two transactions. If no profit is possible, return 0. Note that you cannot engage in multiple transactions simultaneously. # Example: ```python def max_profit(prices): # Your code here # Example usage: print(max_profit([3,3,5,0,0,3,1,4])) # Output: 6 print(max_profit([1,2,3,4,5])) # Output: 4 print(max_profit([7,6,4,3,1])) # Output: 0 print(max_profit([1])) # Output: 0 ``` # Explanation: * In the first example, the maximum profit can be achieved by buying on day `4` at price `0` and selling on day `6` at price `3`, then buying again on day `7` at price `1` and selling on day `8` at price `4`. Therefore, the total profit is `(3-0) + (4-1) = 3 + 3 = 6`. * In the second example, you can just buy at `1` and then sell at `5`, resulting in a single transaction profit of `4`. * In the last example, no profit can be made because the price decreases each day. * The fourth example has only one price day, so no transaction is possible, and the profit is `0`. Your implementation should consider edge cases like: - When the number of days (length of prices list) is less than 2. - When the prices are always decreasing. - When prices contain only one element.
answer:def max_profit(prices): if not prices or len(prices) < 2: return 0 n = len(prices) max_profit_one_txn = [0] * n max_profit_two_txn = [0] * n min_price_so_far = prices[0] for i in range(1, n): min_price_so_far = min(min_price_so_far, prices[i]) max_profit_one_txn[i] = max(max_profit_one_txn[i-1], prices[i] - min_price_so_far) max_price_so_far = prices[-1] for i in range(n-2, -1, -1): max_price_so_far = max(max_price_so_far, prices[i]) max_profit_two_txn[i] = max(max_profit_two_txn[i+1], max_price_so_far - prices[i] + max_profit_one_txn[i]) return max(max_profit_two_txn)
question:A company organizes regular events where employees can participate as either hosts or guests. Each event must have exactly one host and at least one guest. The company keeps a log of which employees have hosted or guest-participated in the past events. Your task is to determine the minimum number of additional employees needed to ensure that future events can always be properly hosted, given the past participation data. A company's log is given as an array where each element represents whether an employee has hosted or participated as a guest in past events. - 'H' denotes that the employee has hosted. - 'G' denotes that the employee has participated as a guest. You need to determine how many additional employees are needed to meet the requirement such that: 1. There is at least one host. 2. There is at least one guest. -----Input----- The first line contains an integer n (1 ≤ n ≤ 1000), the number of employees. The second line contains a string of length n, where each character is either 'H' or 'G'. -----Output----- Output a single integer, the minimum number of additional employees needed to ensure that future events can be hosted with at least one host and one guest. -----Examples----- Input 5 HHHHH Output 1 Input 4 GGGG Output 1 Input 3 HGH Output 0 -----Note----- For the first sample, you need at least one guest, so adding one guest will suffice. For the second sample, you need at least one host, so adding one host will suffice. In the third sample, you already have both hosts and guests. Hence, no additional employees are needed.
answer:def additional_employees_needed(n, log): Determine the minimum number of additional employees needed to ensure that future events can be properly hosted. Parameters: n (int): The number of employees. log (str): A string representing employees participation in past events ('H' for hosts and 'G' for guests). Returns: int: The minimum number of additional employees needed. has_host = 'H' in log has_guest = 'G' in log if has_host and has_guest: return 0 elif has_host: return 1 elif has_guest: return 1 else: return 2
question:Implement a Queue using two stacks stack1 and stack2. Example 1: Input: enqueue(2) enqueue(3) dequeue() enqueue(4) dequeue() Output: 2 3 Explanation: enqueue(2) the queue will be {2} enqueue(3) the queue will be {2, 3} dequeue() dequeued element will be 2 the queue will be {3} enqueue(4) the queue will be {3, 4} dequeue() dequeued element will be 3 Example 2: Input: enqueue(2) dequeue() dequeue() enqueue(3) Output: 2 -1 Your Task: Since this is a function problem, you don't need to take inputs. You are required to complete the two methods enqueue() which takes an integer 'x' as input denoting the element to be enqueued into the queue and dequeue() which returns the integer dequeued from the queue(-1 if the queue is empty). Expected Time Complexity: O(1) for enqueue() and O(N) for dequeue() (or vice-versa). Expected Auxiliary Space: O(1) for both enqueue() and dequeue(). Constraints: 1 <= Number of queries <= 100 1 <= values of the queue <= 100
answer:class QueueUsingStacks: def __init__(self): self.stack1 = [] self.stack2 = [] def enqueue(self, x): self.stack1.append(x) def dequeue(self): if not self.stack2: while self.stack1: self.stack2.append(self.stack1.pop()) if not self.stack2: return -1 return self.stack2.pop()