#include <iostream>
#include <iomanip>
#include <cmath>
#include <string>
#include <cctype>
#include <algorithm>
using namespace std;

// 阶乘计算函数（仅支持非负整数，超出范围返回-1）
long long factorial(int n) {
    if (n < 0) return -1;
    if (n == 0 || n == 1) return 1;
    long long res = 1;
    for (int i = 2; i <= n; i++) {
        res *= i;
        if (res < 0) return -2;
    }
    return res;
}

// 字符串预处理：去除所有括号
string preprocess(string s) {
    s.erase(remove(s.begin(), s.end(), '('), s.end());
    s.erase(remove(s.begin(), s.end(), ')'), s.end());
    return s;
}

// 拆分无空格阶乘（如3!拆分为"3"和"!"）
bool splitFactorial(string &input, string &num_str, string &op) {
    size_t pos = input.find('!');
    if (pos != string::npos && pos > 0) {
        num_str = input.substr(0, pos);
        op = "!";
        return true;
    }
    return false;
}

int main() {
    cout << "===== 增强版科学无限循环计算器（灵活输入） =====" << endl;
    cout << "【双目运算（格式：数字1 运算符 数字2）】" << endl;
    cout << "支持：+（加）、-（减）、*（乘）、/（除）、^（幂运算，如 2^3=8）" << endl;
    cout << "【单目运算（支持灵活格式）】" << endl;
    cout << "支持：sqrt(4)、cos12、5^2、3! 等格式（可无空格、可带括号）" << endl;
    cout << "支持：sin、cos、tan（弧度制）、ln、log10、!（阶乘）" << endl;
    cout << "【退出方式】：输入 q/Q 即可退出计算器" << endl;
    cout << "==============================================" << endl;

    while (true) {
        double num1, num2;
        string op;
        double result;
        bool is_single_op = false;
        bool valid_op = true;
        string full_input;

        cout << "\n请输入表达式：";
        // 读取整行输入
        getline(cin, full_input);
        // 去除首尾空格
        full_input.erase(0, full_input.find_first_not_of(" \t"));
        full_input.erase(full_input.find_last_not_of(" \t") + 1);

        // 判断退出
        if (full_input == "q" || full_input == "Q") {
            cout << "计算器已退出，感谢使用！" << endl;
            break;
        }

        // 预处理：去除括号
        string processed = preprocess(full_input);
        // 拆分输入项（处理无空格场景）
        string first_part, second_part, third_part;
        size_t pos1 = processed.find_first_of(" +-*/^!");
        size_t pos2 = string::npos;

        // 场景1：单目运算符开头（如sqrt4、sin12）
        if (processed.substr(0, 4) == "sqrt" || processed.substr(0, 3) == "sin" ||
            processed.substr(0, 3) == "cos" || processed.substr(0, 3) == "tan" ||
            processed.substr(0, 2) == "ln" || processed.substr(0, 5) == "log10") {
            is_single_op = true;
            if (processed.substr(0, 4) == "sqrt") {
                op = "sqrt";
                num1 = atof(processed.substr(4).c_str());
            } else if (processed.substr(0, 3) == "sin") {
                op = "sin";
                num1 = atof(processed.substr(3).c_str());
            } else if (processed.substr(0, 3) == "cos") {
                op = "cos";
                num1 = atof(processed.substr(3).c_str());
            } else if (processed.substr(0, 3) == "tan") {
                op = "tan";
                num1 = atof(processed.substr(3).c_str());
            } else if (processed.substr(0, 2) == "ln") {
                op = "ln";
                num1 = atof(processed.substr(2).c_str());
            } else if (processed.substr(0, 5) == "log10") {
                op = "log10";
                num1 = atof(processed.substr(5).c_str());
            }
        }
        // 场景2：阶乘（如3!、5!）
        else if (splitFactorial(processed, first_part, op)) {
            is_single_op = true;
            num1 = atof(first_part.c_str());
        }
        // 场景3：平方（如5^2、10^2）
        else if ((pos1 = processed.find("^2")) != string::npos) {
            is_single_op = true;
            op = "^2";
            num1 = atof(processed.substr(0, pos1).c_str());
        }
        // 场景4：双目运算（如2+3、4^5）
        else {
            is_single_op = false;
            pos1 = processed.find_first_of("+-*/^");
            if (pos1 == string::npos) {
                cout << "无效输入，请重新输入！" << endl;
                continue;
            }
            op = processed.substr(pos1, 1);
            num1 = atof(processed.substr(0, pos1).c_str());
            num2 = atof(processed.substr(pos1 + 1).c_str());
        }

        // 执行计算逻辑（与原有代码一致，此处省略重复部分，直接复用原有判断）
        if (is_single_op) {
            if (op == "sqrt") {
                if (num1 < 0) {
                    cout << "错误：负数无法开平方！" << endl;
                    valid_op = false;
                } else {
                    result = sqrt(num1);
                }
            } else if (op == "sin") {
                result = sin(num1);
            } else if (op == "cos") {
                result = cos(num1);
            } else if (op == "tan") {
                result = tan(num1);
            } else if (op == "ln") {
                if (num1 <= 0) {
                    cout << "错误：自然对数的输入必须大于0！" << endl;
                    valid_op = false;
                } else {
                    result = log(num1);
                }
            } else if (op == "log10") {
                if (num1 <= 0) {
                    cout << "错误：常用对数的输入必须大于0！" << endl;
                    valid_op = false;
                } else {
                    result = log10(num1);
                }
            } else if (op == "^2") {
                result = num1 * num1;
            } else if (op == "!") {
                int n = static_cast<int>(num1);
                if (n != num1) {
                    cout << "错误：阶乘仅支持整数输入！" << endl;
                    valid_op = false;
                } else {
                    long long fact_res = factorial(n);
                    if (fact_res == -1) {
                        cout << "错误：阶乘仅支持非负整数！" << endl;
                        valid_op = false;
                    } else if (fact_res == -2) {
                        cout << "错误：阶乘数值过大，超出范围！" << endl;
                        valid_op = false;
                    } else {
                        cout << num1 << "! = " << fact_res << endl;
                        valid_op = false;
                    }
                }
            }
        } else {
            if (op == "+") {
                result = num1 + num2;
            } else if (op == "-") {
                result = num1 - num2;
            } else if (op == "*") {
                result = num1 * num2;
            } else if (op == "/") {
                if (num2 == 0) {
                    cout << "错误：除数不能为0！" << endl;
                    valid_op = false;
                } else {
                    result = num1 / num2;
                }
            } else if (op == "^") {
                result = pow(num1, num2);
            } else {
                cout << "错误：无效双目运算符！" << endl;
                valid_op = false;
            }
        }

        if (valid_op && op != "!") {
            cout << "计算结果：";
            if (is_single_op) {
                if (op == "^2") {
                    cout << num1 << " ^2 = " << fixed << setprecision(4) << result << endl;
                } else {
                    cout << op << "(" << num1 << ") = " << fixed << setprecision(4) << result << endl;
                }
            } else {
                cout << num1 << " " << op << " " << num2 << " = " << fixed << setprecision(4) << result << endl;
            }
        }
    }

    return 0;
}