answer:# Define a class for LL1 Parser class LL1Parser: # Initialize the parser with a grammar, a set of terminals, and a set of non-terminals def __init__(self, grammar, terminals, non_terminals): self.grammar = grammar self.terminals = terminals self.non_terminals = non_terminals # Initialize the LL1 table self.ll1_table = {} # Fill the LL1 table with the FIRST and FOLLOW sets self.fill_ll1_table() # Fill the LL1 table with the FIRST and FOLLOW sets def fill_ll1_table(self): # Calculate the FIRST sets for each non-terminal first_sets = self.calculate_first_sets() # Calculate the FOLLOW sets for each non-terminal follow_sets = self.calculate_follow_sets() # Generate the LL1 table for non_terminal in self.non_terminals: for terminal in self.terminals.union({''}): # Check if the non-terminal produces the terminal in its FIRST set if terminal in first_sets[non_terminal]: productions = [p for p in self.grammar[non_terminal] if p[0] == terminal] # Add the productions to the LL1 table entry self.ll1_table[(non_terminal, terminal)] = productions # Check if the non-terminal produces the terminal in its FOLLOW set and the FIRST set is empty elif terminal in follow_sets[non_terminal] and not first_sets[non_terminal]: productions = [p for p in self.grammar[non_terminal] if p[0] == terminal] # Add the productions to the LL1 table entry self.ll1_table[(non_terminal, terminal)] = productions # Add an error entry to the LL1 table else: self.ll1_table[(non_terminal, terminal)] = 'error' # Calculate the FIRST sets for each non-terminal def calculate_first_sets(self): first_sets = {} # Initialize the FIRST sets with empty sets for each non-terminal for non_terminal in self.non_terminals: first_sets[non_terminal] = set() # Calculate the FIRST sets iteratively while True: has_changed = False for non_terminal in self.non_terminals: for production in self.grammar[non_terminal]: # If the first symbol is a terminal, add it to the FIRST set if production[0] in self.terminals: if production[0] not in first_sets[non_terminal]: first_sets[non_terminal].add(production[0]) has_changed = True # If the first symbol is a non-terminal, add the FIRST set of that non-terminal to the current FIRST set else: for symbol in production: if symbol == non_terminal: break if symbol in self.terminals: if symbol not in first_sets[non_terminal]: first_sets[non_terminal].add(symbol) has_changed = True break if self.is_nullable(symbol): for s in first_sets[symbol]: if s not in first_sets[non_terminal]: first_sets[non_terminal].add(s) has_changed = True else: break if not bool(self.grammar[non_terminal]): first_sets[non_terminal].add('epsilon') has_changed = True if not has_changed: break return first_sets # Calculate the FOLLOW sets for each non-terminal def calculate_follow_sets(self): follow_sets = {} # Initialize the FOLLOW sets with empty sets for each non-terminal for non_terminal in self.non_terminals: follow_sets[non_terminal] = set() # Add the end-of-input symbol to the start symbol's FOLLOW set follow_sets[list(self.non_terminals)[0]].add('') # Calculate the FOLLOW sets iteratively while True: has_changed = False for non_terminal in self.non_terminals: for production in self.grammar[non_terminal]: for i in range(len(production)): symbol = production[i] # If the symbol is a non-terminal, add the FOLLOW set of the current non-terminal to its FIRST set if symbol in self.non_terminals: if i == len(production) - 1: for s in follow_sets[non_terminal]: if s not in follow_sets[symbol]: follow_sets[symbol].add(s) has_changed = True else: for j in range(i+1, len(production)): if production[j] in self.terminals: if production[j] not in follow_sets[symbol]: follow_sets[symbol].add(production[j]) has_changed = True break else: for s in self.first_sets[production[j]]: if s != 'epsilon' and s not in follow_sets[symbol]: follow_sets[symbol].add(s) has_changed = True if 'epsilon' not in self.first_sets[production[j]]: break elif j == len(production) - 1: for s in follow_sets[non_terminal]: if s not in follow_sets[symbol]: follow_sets[symbol].add(s) has_changed = True else: continue if not has_changed: break return follow_sets # Check if a symbol is nullable def is_nullable(self, symbol): if symbol in self.terminals: return False elif not bool(self.grammar[symbol]): return True else: for production in self.grammar[symbol]: for s in production: if not self.is_nullable(s): break else: return True return False # Parse a given input string def parse(self, input_str): stack = [''] input_str += '' index = 0 while stack: top = stack.pop() curr = input_str[index] if top in self.terminals: if top == curr: index += 1 else: return False elif (top, curr) in self.ll1_table: if self.ll1_table[(top, curr)] == 'epsilon': continue elif self.ll1_table[(top, curr)] == 'error': return False else: for symbol in reversed(self.ll1_table[(top, curr)]): stack.append(symbol) else: return False return index == len(input_str) - 1

answer:小型超市管理系统的系统分层结构图可以分为四个层次，包括： 1. 用户界面层：这是系统的最顶层，负责和用户进行交互。包括用户登录、商品查询、购物车管理、结算等功能模块。 2. 应用逻辑层：负责处理用户界面层传来的请求，调用对应的业务逻辑处理模块。包括用户认证、商品分类、商品销售等模块。 3. 业务逻辑层：负责实现应用逻辑层的业务逻辑，对数据进行处理并返回结果。包括用户管理、商品管理、销售管理、库存管理等模块。 4. 数据持久层：负责将系统中的数据存储到数据库中，包括用户信息、商品信息、销售记录、库存信息等模块。 整个系统的分层结构图如下： ``` ------------------------------------ | 用户界面层 | ------------------------------------ | 应用逻辑层 | ------------------------------------ | 业务逻辑层 | ------------------------------------ | 数据持久层 | ------------------------------------ ``` 从上到下依次为用户界面层、应用逻辑层、业务逻辑层和数据持久层。用户界面层和应用逻辑层之间进行请求和响应的传递，应用逻辑层和业务逻辑层之间进行函数调用和数据传递，业务逻辑层和数据持久层之间进行数据存储和读取。

answer:会计电算化是指利用计算机和相关软件进行会计业务的处理、记录、汇总、报告和分析。在现代企业管理中，会计电算化已成为不可或缺的工具。以下是会计电算化在会计岗位的应用： 1. 会计账簿的电算化处理，如账务录入、账目分析、账务汇总、报表生成等； 2. 会计凭证的自动生成和处理，能够提高会计凭证的准确性和效率，减少出错的可能性； 3. 财务信息的报表制作，如资产负债表、利润表、现金流量表等，这些报表对于企业内部管理和对外财务报告都很重要； 4. 税务申报的电子化处理，如增值税申报、所得税申报等，使税务申报流程更加便捷，减少纳税人的工作量； 5. 管理会计分析的电子化处理，如成本核算、预算编制、市场营销分析、业绩考核等，为企业决策和管理提供数据支持。 可以看出，会计电算化在会计岗位的应用范围广泛，不仅提高了工作效率和精度，也为企业的财务管理和决策提供了有力支持。

answer:固定资产是企业的重要资产之一，为了保障企业资产的安全和管理的准确性，会计人员需要定期对固定资产进行盘点。以下是固定资产盘点的流程： 1. 制定盘点方案：根据企业实际情况，制定盘点方案。方案中应包括盘点时间、盘点人员、盘点范围、盘点方式、盘点工具和程序等内容。 2. 调查资料准备：收集资产设备购置发票、收据、卡片、存根等相关信息资料，并进行审核和整理。 3. 财产账目整理：将固定资产的账面凭证汇编整理好，准备核对。 4. 实地调查：到各个部门、车间、办公室等实地调查和盘点各类固定资产，记录固定资产名称、规格、数量、贬值方法、现值、存放地点、使用状况等。 5. 盘点结果整理：将盘点结果汇总整理，生成固定资产台账。 6. 盘点差异处理：若盘点后发现存在资产损失、遗失、错报等情况，则需要进行认定和处理，进行现场核定和确认。 7. 盘点报告：完成盘点后，会计人员需要将盘点结果及差异处理报告上报企业领导层，并及时与相关部门沟通，处理相关问题。 8. 审计核验：企业财务部门应进行审计核验，确认固定资产的准确性和真实性。若有问题，则需要及时整改。 以上就是固定资产盘点的一般程序流程，会计人员需要认真履行其职责，保障固定资产的安全和准确性。