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internbootcamp/bootcamp/cpythonindentation/cpythonindentation.py

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+"""# 
+
+### 谜题描述
+In Python, code blocks don't have explicit begin/end or curly braces to mark beginning and end of the block. Instead, code blocks are defined by indentation.
+
+We will consider an extremely simplified subset of Python with only two types of statements.
+
+Simple statements are written in a single line, one per line. An example of a simple statement is assignment.
+
+For statements are compound statements: they contain one or several other statements. For statement consists of a header written in a separate line which starts with \"for\" prefix, and loop body. Loop body is a block of statements indented one level further than the header of the loop. Loop body can contain both types of statements. Loop body can't be empty.
+
+You are given a sequence of statements without indentation. Find the number of ways in which the statements can be indented to form a valid Python program.
+
+Input
+
+The first line contains a single integer N (1 ≤ N ≤ 5000) — the number of commands in the program. N lines of the program follow, each line describing a single command. Each command is either \"f\" (denoting \"for statement\") or \"s\" (\"simple statement\"). It is guaranteed that the last line is a simple statement.
+
+Output
+
+Output one line containing an integer - the number of ways the given sequence of statements can be indented modulo 109 + 7. 
+
+Examples
+
+Input
+
+4
+s
+f
+f
+s
+
+
+Output
+
+1
+
+
+Input
+
+4
+f
+s
+f
+s
+
+
+Output
+
+2
+
+Note
+
+In the first test case, there is only one way to indent the program: the second for statement must be part of the body of the first one.
+    
+    
+      
+    simple statement  
+    for statement  
+        for statement  
+            simple statement  
+    
+
+In the second test case, there are two ways to indent the program: the second for statement can either be part of the first one's body or a separate statement following the first one.
+    
+    
+      
+    for statement  
+        simple statement  
+        for statement  
+            simple statement  
+    
+
+or
+    
+    
+      
+    for statement  
+        simple statement  
+    for statement  
+        simple statement  
+    
+
+Here is a reference code to solve this task. You can use this to help you genereate cases or validate the solution.
+```python
+mod = 10**9+7
+n = input()
+x = [1]
+for i in range(n):
+	s = raw_input()
+	if s=='f':
+		x.insert(0,0)
+	else:
+		for i in range(len(x)-2,-1,-1):
+			x[i] = (x[i]+x[i+1])%mod
+print x[0]
+```
+
+
+请完成上述谜题的训练场环境类实现，包括所有必要的方法。
+"""
+
+from bootcamp import Basebootcamp
+from bootcamp import Basebootcamp
+import random
+import re
+
+class Cpythonindentationbootcamp(Basebootcamp):
+    def __init__(self, min_n=1, max_n=10):
+        if min_n < 1:
+            raise ValueError("min_n must be at least 1")
+        if max_n > 5000:
+            raise ValueError("max_n cannot exceed 5000")
+        self.min_n = max(1, min_n)
+        self.max_n = min(5000, max(max_n, self.min_n))
+    
+    def case_generator(self):
+        n = random.randint(self.min_n, self.max_n)
+        commands = [random.choice(['f', 's']) for _ in range(n-1)]
+        commands.append('s')  # Ensure last command is 's'
+        return {
+            'n': n,
+            'commands': commands
+        }
+    
+    @staticmethod
+    def prompt_func(question_case):
+        input_lines = [str(question_case['n'])] + question_case['commands']
+        input_example = '\n'.join(input_lines)
+        prompt = f"""你是编程专家，需要解决一个关于Python缩进规则的谜题。请仔细阅读问题描述，并给出正确的答案。
+
+问题描述：
+在Python中，代码块由缩进定义，而没有显式的开始/结束符号。我们考虑一个极简化的Python子集，只有两种语句：简单语句（s）和for语句（f）。简单语句占据单独一行。for语句是复合语句，包含一个头部和一个循环体。循环体必须比for语句的头部缩进一级，且不能为空。
+
+给定一个由's'和'f'组成的命令序列，最后一个命令一定是's'。你需要计算所有可能的有效缩进方式的数量，结果对10^9+7取模。
+
+输入格式：
+第一行包含整数N（命令数）。随后N行，每行是'f'或's'。
+
+输出格式：
+输出一个整数，表示有效方式数取模后的结果。
+
+示例输入1：
+4
+s
+f
+f
+s
+
+示例输出1：
+1
+
+示例输入2：
+4
+f
+s
+f
+s
+
+示例输出2：
+2
+
+现在，请你解决以下输入案例：
+
+输入：
+{input_example}
+
+请将你的最终答案放在[answer]标签内，例如：[answer]123[/answer]。"""
+        return prompt
+    
+    @staticmethod
+    def extract_output(output):
+        matches = re.findall(r'\[answer\](.*?)\[/answer\]', output, re.DOTALL)
+        if not matches:
+            return None
+        last_match = matches[-1].strip()
+        try:
+            return int(last_match)
+        except ValueError:
+            return None
+    
+    @classmethod
+    def _verify_correction(cls, solution, identity):
+        mod = 10**9 + 7
+        commands = identity['commands']
+        dp = [1]
+        for stmt in commands:
+            if stmt == 'f':
+                dp.insert(0, 0)
+            else:
+                # Propagate the sum backwards
+                for i in range(len(dp)-2, -1, -1):
+                    dp[i] = (dp[i] + dp[i+1]) % mod
+        correct_answer = dp[0] % mod if dp else 0
+        try:
+            return int(solution) == correct_answer
+        except (ValueError, TypeError):
+            return False