answer:def longest_chain(words): Returns the length of the longest chain of characters from the given list of strings. All characters in the longest chain must appear in non-decreasing order. :param words: List of strings :return: Integer length of the longest chain # Concatenate all words into one chain and sort it all_chars = ''.join(words) sorted_chars = sorted(all_chars) # The length of the sorted characters list is the length of the longest chain return len(sorted_chars)

answer:from typing import List from collections import deque def minSteps(grid: List[List[int]]) -> int: Returns the minimum number of steps required to reach the bottom-right corner from the top-left corner of the grid. If it is impossible to reach the bottom-right corner, returns -1. if not grid or not grid[0] or grid[0][0] == 0 or grid[-1][-1] == 0: return -1 n, m = len(grid), len(grid[0]) directions = [(1, 0), (0, 1), (-1, 0), (0, -1)] queue = deque([(0, 0)]) steps = 0 while queue: for _ in range(len(queue)): x, y = queue.popleft() if (x, y) == (n-1, m-1): return steps for dx, dy in directions: nx, ny = x + dx, y + dy if 0 <= nx < n and 0 <= ny < m and grid[nx][ny] == 1: queue.append((nx, ny)) grid[nx][ny] = 0 # Mark as visited steps += 1 return -1

answer:def rearrange_to_divisible_by_3(s): Given a string s containing only digits, determine if it can be rearranged into a number that is divisible by 3. Return the largest possible such number or -1 if it's not possible. # Convert the string into a list of digits digits = [int(char) for char in s] # Sum of the digits digit_sum = sum(digits) # Check if sum of the digits is divisible by 3 if digit_sum % 3 != 0: return -1 # Sort digits in descending order to form the largest number possible digits.sort(reverse=True) # Join sorted digits and form the largest number largest_number = ''.join(map(str, digits)) return largest_number

answer:from typing import List class SubmatrixSumFinder: def __init__(self, matrix: List[List[int]]): if not matrix or not matrix[0]: raise ValueError("Matrix cannot be empty") self.matrix = matrix self.m = len(matrix) self.n = len(matrix[0]) # Initialize the prefix sum matrix. self.prefix_sum = [[0] * (self.n + 1) for _ in range(self.m + 1)] # Calculate the prefix sum for each cell. for i in range(1, self.m + 1): for j in range(1, self.n + 1): self.prefix_sum[i][j] = (self.matrix[i - 1][j - 1] + self.prefix_sum[i - 1][j] + self.prefix_sum[i][j - 1] - self.prefix_sum[i - 1][j - 1]) def sumRegion(self, row1: int, col1: int, row2: int, col2: int) -> int: return (self.prefix_sum[row2 + 1][col2 + 1] - self.prefix_sum[row1][col2 + 1] - self.prefix_sum[row2 + 1][col1] + self.prefix_sum[row1][col1])