{ "data": { "question": { "questionId": "1197", "questionFrontendId": "1106", "categoryTitle": "Algorithms", "boundTopicId": 11240, "title": "Parsing A Boolean Expression", "titleSlug": "parsing-a-boolean-expression", "content": "

A boolean expression is an expression that evaluates to either true or false. It can be in one of the following shapes:

\n\n\n\n

Given a string expression that represents a boolean expression, return the evaluation of that expression.

\n\n

It is guaranteed that the given expression is valid and follows the given rules.

\n\n

 

\n

Example 1:

\n\n
\nInput: expression = "&(|(f))"\nOutput: false\nExplanation: \nFirst, evaluate |(f) --> f. The expression is now "&(f)".\nThen, evaluate &(f) --> f. The expression is now "f".\nFinally, return false.\n
\n\n

Example 2:

\n\n
\nInput: expression = "|(f,f,f,t)"\nOutput: true\nExplanation: The evaluation of (false OR false OR false OR true) is true.\n
\n\n

Example 3:

\n\n
\nInput: expression = "!(&(f,t))"\nOutput: true\nExplanation: \nFirst, evaluate &(f,t) --> (false AND true) --> false --> f. The expression is now "!(f)".\nThen, evaluate !(f) --> NOT false --> true. We return true.\n
\n\n

 

\n

Constraints:

\n\n\n", "translatedTitle": "解析布尔表达式", "translatedContent": "

布尔表达式 是计算结果不是 true 就是 false 的表达式。有效的表达式需遵循以下约定：

\n\n\n\n

给你一个以字符串形式表述的 布尔表达式 expression，返回该式的运算结果。

\n\n

题目测试用例所给出的表达式均为有效的布尔表达式，遵循上述约定。

\n\n

 

\n\n

示例 1：

\n\n
\n输入：expression = \"&(|(f))\"\n输出：false\n解释：\n首先，计算 |(f) --> f ，表达式变为 \"&(f)\" 。\n接着，计算 &(f) --> f ，表达式变为 \"f\" 。\n最后，返回 false 。\n
\n\n

示例 2：

\n\n
\n输入：expression = \"|(f,f,f,t)\"\n输出：true\n解释：计算 (false OR false OR false OR true) ，结果为 true 。\n
\n\n

示例 3：

\n\n
\n输入：expression = \"!(&(f,t))\"\n输出：true\n解释：\n首先，计算 &(f,t) --> (false AND true) --> false --> f ，表达式变为 \"!(f)\" 。\n接着，计算 !(f) --> NOT false --> true ，返回 true 。\n
\n\n

 

\n\n

提示：

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