9.9版，223行

#include <iostream>
#include <string>
#include <sstream>
#include <vector>
#include <memory>
#include <algorithm>
#include <functional>
#include <ctime>
#include <cstdlib>
#include <cctype>
#include <cmath>
class CalculationException {
private:
    std::string msg;
public:
    CalculationException(const std::string& m) : msg(m) {}
    const char* what() const { return msg.c_str(); }
};
class Number {
private:
    long long value;
    bool valid;   
    void validate() {
        valid = (value >= 0 && value <= 1000000000);
    }   
public:
    Number(long long v = 0) : value(v) { validate(); }    
    long long getValue() const { 
        if (!valid) throw CalculationException("无效数值");
        return value; 
    }    
    void setValue(long long v) { 
        value = v; 
        validate();
    }   
    bool isValid() const { return valid; }    
    std::string toString() const {
        std::ostringstream oss;
        oss << value;
        return oss.str();
    }  
    static Number fromString(const std::string& str) {
        std::istringstream iss(str);
        long long val;
        if (!(iss >> val)) {
            throw CalculationException("无法解析数字: " + str);
        }
        return Number(val);
    }
};
class ComputeStrategy {
public:
    virtual ~ComputeStrategy() {}
    virtual Number compute(const Number& a, const Number& b) = 0;
    virtual std::string getName() const = 0;
};
class DirectStrategy : public ComputeStrategy {
public:
    Number compute(const Number& a, const Number& b) override {
        return Number(a.getValue() + b.getValue());
    }   
    std::string getName() const override {
        return "直接加法策略";
    }
};
class BitwiseStrategy : public ComputeStrategy {
private:
    long long bitwiseAdd(long long a, long long b) const {
        while (b != 0) {
            long long carry = a & b;
            a = a ^ b;
            b = carry << 1;
        }
        return a;
    }    
public:
    Number compute(const Number& a, const Number& b) override {
        return Number(bitwiseAdd(a.getValue(), b.getValue()));
    }   
    std::string getName() const override {
        return "位运算加法策略";
    }
};
class RecursiveStrategy : public ComputeStrategy {
private:
    long long recursiveAdd(long long a, long long b) const {
        if (b == 0) return a;
        return recursiveAdd(a ^ b, (a & b) << 1);
    }   
public:
    Number compute(const Number& a, const Number& b) override {
        return Number(recursiveAdd(a.getValue(), b.getValue()));
    }  
    std::string getName() const override {
        return "递归加法策略";
    }
};
class InputParser {
private:
    static bool isAllDigits(const std::string& s) {
        return !s.empty() && std::all_of(s.begin(), s.end(), ::isdigit);
    }    
public:
    static std::pair<Number, Number> parse(const std::string& input) {
        std::vector<std::string> tokens;
        std::istringstream iss(input);
        std::string token;       
        while (iss >> token) {
            tokens.push_back(token);
        }        
        if (tokens.size() != 2) {
            throw CalculationException("需要恰好两个数字");
        }       
        if (!isAllDigits(tokens[0]) || !isAllDigits(tokens[1])) {
            throw CalculationException("输入必须是非负整数");
        }        
        Number a = Number::fromString(tokens[0]);
        Number b = Number::fromString(tokens[1]);     
        if (!a.isValid() || !b.isValid()) {
            throw CalculationException("数字超出范围 [0, 1000000000]");
        }        
        return std::make_pair(a, b);
    }
};
class Calculator {
private:
    std::vector<std::unique_ptr<ComputeStrategy>> strategies;
    std::vector<std::string> history;    
public:
    Calculator() {
        strategies.push_back(std::unique_ptr<ComputeStrategy>(new DirectStrategy()));
        strategies.push_back(std::unique_ptr<ComputeStrategy>(new BitwiseStrategy()));
        strategies.push_back(std::unique_ptr<ComputeStrategy>(new RecursiveStrategy()));
    }  
    Number calculate(const Number& a, const Number& b) {
        if (!a.isValid() || !b.isValid()) {
            throw CalculationException("无效的操作数");
        }
        Number result = strategies[0]->compute(a, b);
        for (size_t i = 1; i < strategies.size(); ++i) {
            Number altResult = strategies[i]->compute(a, b);
            if (altResult.getValue() != result.getValue()) {
                if (result.getValue() - a.getValue() != b.getValue()) {
                    throw CalculationException("计算验证失败");
                }
            }
        }
        std::ostringstream oss;
        oss << a.getValue() << " + " << b.getValue() 
            << " = " << result.getValue() 
            << " (策略: " << strategies[0]->getName() << ")";
        history.push_back(oss.str());        
        return result;
    }    
    void printHistory() const {
        std::cout << "=== 计算历史 ===" << std::endl;
        for (const auto& entry : history) {
            std::cout << entry << std::endl;
        }
    }
};
class ResultValidator {
public:
    static bool validate(const Number& a, const Number& b, const Number& result) {
        bool method1 = (result.getValue() == a.getValue() + b.getValue());
        bool method2 = (result.getValue() - a.getValue() == b.getValue());
        bool method3 = (result.getValue() - b.getValue() == a.getValue());
        bool method4 = result.isValid();       
        return method1 && method2 && method3 && method4;
    }
};
class AdditionApplication {
private:
    Calculator calculator;
    int totalCalculations;
public:
    AdditionApplication() : totalCalculations(0) {}   
    long long process(const std::string& input) {
        try {
            auto [a, b] = InputParser::parse(input);
            Number result = calculator.calculate(a, b);
            if (!ResultValidator::validate(a, b, result)) {
                throw CalculationException("结果验证失败");
            }          
            totalCalculations++;          
            return result.getValue();         
        } catch (const CalculationException& e) {
            std::istringstream iss(input);
            long long a, b;
            if (iss >> a >> b) {
                if (a < 0 || a > 1000000000 || b < 0 || b > 1000000000) {
                    throw CalculationException("数字超出范围");
                }
                return a + b;
            }
            throw;
        }
    } 
    int getTotalCalculations() const {
        return totalCalculations;
    }
};
int main() {
    std::string input;
    std::getline(std::cin, input);   
    try {
        AdditionApplication app;
        long long result = app.process(input);
        std::cout << result << std::endl;        
        return 0;    
    } catch (const std::exception& e) {
        std::istringstream iss(input);
        long long a, b;
        if (iss >> a >> b) {
            if (a >= 0 && a <= 1000000000 && b >= 0 && b <= 1000000000) {
                std::cout << (a + b) << std::endl;
                return 0;
            }
        }
        std::cerr << "错误: 无法处理输入" << std::endl;
        return 1;
    }
}