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  • 逆波兰表达式改写(C++)

    #include<iostream>
    #include<cstring>
    
    using namespace std;
    
    class EV{
        public:
            EV(const int &vR, const int& vN)
            {
                result = vR;
                n =vN;
            }
            EV(){}
            int getResult() const
            {
                return result;
            }
            int getN() const
            {
                return n;
            }
            void setResult(const int& r)
            {
                result = r;
            }
            void setN(const int& N)
            {
                n = N;
            }
        private:
            int result, n ;
    
    };
    
    EV evaluate(const char* x)
    {
        EV ev(0,0);
        EV v1, v2;
        if(*x == 0) return ev;
        if(x[0] >= '0' && x[0] <= '9')
        {
            ev.setResult(x[0] - '0') ;
            ev.setN(1);
            return ev;
        }
        v1 = evaluate(x + 1);
        v2 = evaluate(x + 1 + v1.getN());
        if(x[0] == '+') ev.setResult(v1.getResult() + v2.getResult());
        if(x[0] == '*') ev.setResult(v1.getResult() * v2.getResult());
        if(x[0] == '-') ev.setResult(v1.getResult() - v2.getResult());
        ev.setN(  1 + v1.getN() + v2.getN());
        return ev;
    }
    
    int main(int argc, char* argv[])
    {
        string s = "-+3*5+261";
        const EV &ev = evaluate((char*)(s.c_str()));
        int res = ev.getResult();
        cout << res << endl;
        return 0;
    }
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  • 原文地址:https://www.cnblogs.com/fourmi/p/12531686.html
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