C++说明逻辑表达式的定义如下：单个true或false都是逻辑表达式；如果S及T是逻辑表达式那么S and T也是逻辑表达式；如果S及T是逻辑表达式那么S or T也是逻辑表达式。对逻辑表达式求值前需要确定and与or运算的优先级：若规定先算and再算or则以下表达式的值为 true or false and false or false ~~~~~~~~~~~~~~~

#include #include #include using namespace std;

bool evaluateExpression(string expression, bool conjunctionFirst) { stack operands; stack operators;

for (int i = 0; i < expression.length(); i++) {
    if (expression[i] == ' ') {
        continue;
    } else if (expression[i] == 'true') {
        operands.push(true);
    } else if (expression[i] == 'false') {
        operands.push(false);
    } else if (expression[i] == 'and' || expression[i] == 'or') {
        operators.push(expression[i]);
    } else if (expression[i] == '(') {
        operators.push(expression[i]);
    } else if (expression[i] == ')') {
        while (!operators.empty() && operators.top() != '(') {
            char op = operators.top();
            operators.pop();

            bool operand2 = operands.top();
            operands.pop();
            bool operand1 = operands.top();
            operands.pop();

            if (op == 'and') {
                operands.push(operand1 && operand2);
            } else if (op == 'or') {
                operands.push(operand1 || operand2);
            }
        }

        if (!operators.empty()) {
            operators.pop(); //pop '('
        }
    }
}

while (!operators.empty()) {
    char op = operators.top();
    operators.pop();

    bool operand2 = operands.top();
    operands.pop();
    bool operand1 = operands.top();
    operands.pop();

    if (op == 'and') {
        operands.push(operand1 && operand2);
    } else if (op == 'or') {
        operands.push(operand1 || operand2);
    }
}

return operands.top();

}

int main() { string expression; getline(cin, expression);

bool resultConjunctionFirst = evaluateExpression(expression, true);
bool resultDisjunctionFirst = evaluateExpression(expression, false);

cout << (resultConjunctionFirst ? "true" : "false") << endl;
cout << (resultDisjunctionFirst ? "true" : "false") << endl;

return 0;