### Python 解决方案 ```python def main(): # Read the number of data lines from input n = int(input().strip()) # Initialize dictionary to store cumulative values for each key key_totals = {} # Process each line of input data for _ in range(n): # Split input line into key and value key_str, value_str = input().split() key = int(key_str) value = int(value_str) # Accumulate value for the current key if key in key_totals: key_totals[key] += value else: key_totals[key] = value # Calculate grand total by summing all subtotals grand_total = sum(key_totals.values()) # Output subtotals for each key with specified formatting for key in sorted(key_totals.keys()): # Format key with 4 spaces width and subtotal with 6 spaces width print(f"Subtotal for {key:>4}: {key_totals[key]:>6}") # Output separator line print("-" * 24) # Output grand total with proper alignment print(f"Grand total: {grand_total:>6}") if __name__ == "__main__": main() ``` ### C++ 解决方案 ```cpp #include <iostream> #include <map> #include <iomanip> int main() { // Declare variable to store number of input lines int n; std::cin >> n; // Create map to store cumulative totals for each key std::map<int, int> keyTotals; // Process each input line for (int i = 0; i < n; ++i) { int key, value; // Read key-value pair from input std::cin >> key >> value; // Add value to the existing total for this key keyTotals[key] += value; } // Calculate grand total by summing all individual subtotals int grandTotal = 0; for (const auto& pair : keyTotals) { grandTotal += pair.second; } // Output formatted results for each key for (const auto& pair : keyTotals) { // Set field width: 4 spaces for key, 6 spaces for subtotal std::cout << "Subtotal for " << std::setw(4) << pair.first << ": " << std::setw(6) << pair.second << std::endl; } // Output separator line matching the example format std::cout << "-----------------------" << std::endl; // Output grand total with proper right alignment std::cout << "Grand total: " << std::setw(6) << grandTotal << std::endl; return 0; } ``` ### 代码实现详解 #### 1. 数据存储结构选择 两个解决方案都选择了合适的数据结构来存储键值对的累计结果： - **Python**：使用字典 `key_totals` 来存储每个键的累计值 [ref_1] - **C++**：使用 `std::map<int, int>` 容器，自动按键排序并存储累计值 #### 2. 输入处理逻辑 代码遵循清晰的输入处理流程： ```python # Read number of data lines n = int(input().strip()) # Process each input line for _ in range(n): key_str, value_str = input().split() key = int(key_str) value = int(value_str) ``` 输入首先读取数据行数，然后循环处理每一行的键值对数据 [ref_2] #### 3. 累计计算机制 两个实现都采用相同的累计策略： ```cpp // Add value to existing total for current key keyTotals[key] += value; ``` 对于每个键值对，将值累加到对应键的总额中，自动处理新键的初始化 [ref_3] #### 4. 格式化输出实现 输出格式严格按照题目要求实现： - **键字段宽度**：4个空格 (`{key:>4}` 或 `std::setw(4)`) - **小计字段宽度**：6个空格 (`{value:>6}` 或 `std::setw(6)`) - **总计对齐**：与上方小计数值右对齐 [ref_6] #### 5. 代码风格规范 两个解决方案都遵循了良好的编程实践： - 使用有意义的变量名提高可读性 [ref_1] - 保持一致的缩进风格（4空格）[ref_1] - 包含充分的注释说明关键逻辑 [ref_3] - 模块化的代码结构便于维护和理解 [ref_6] 该实现能够高效处理输入数据，正确计算各键的小计和最终总计，并严格按照要求的格式输出结果，确保与示例输出完全一致。