调度场算法-表达式计算

╰半橙微兮° 2022-05-13 14:56 137阅读 0赞

也不是什么新的东西把，调度场也不说了，就说说我写过的三个版本表达式的成长吧

第一个简单计算器，没有括号没有单独考虑加减乘除优先级

第二个等价表达式主要是没有值吧，全代固定变量，然后没有除法

列出来：

**\[1\]简单计算器：**[字符串处理之简单计算器][Link 1]

**\[2\]等价表达式：**[转逆波兰表达式-OpenJudge\[等价表达式\]][-OpenJudge]

慢慢填坑，这个表达式计算用到 \[1\]的截取浮点数方法，加上\[2\]的转逆波兰及逆波兰表达式求值，直接贴代码了

#include<bits/stdc++.h>
    using namespace std;
    
    void Tranfer_Equal(string Init_Equal,string& Equal,queue<double>& Num_Que)
    {
        stack<char> Signal;
    
        int i=0;
        int Point_Flag=0;
        int Pow=10;
        double Number=0;
    
        while(Init_Equal[i]!='#')
        {
            if((Init_Equal[i]>='0'&&Init_Equal[i]<='9')||Init_Equal[i]=='.')
            {
                if(Init_Equal[i]=='.')
                {
                    Point_Flag=1;
                    Pow=10;
                    i++;
                    continue;
                }
                if(Point_Flag)
                {
                    Number+=((Init_Equal[i]-'0')*1.0)/Pow;
                    Pow*=10;
                }
                else
                    Number=Number*10+(Init_Equal[i]-'0');
    
                if((Init_Equal[i+1]>'9'||Init_Equal[i+1]<'0')&&Init_Equal[i+1]!='.')
                {
                    Equal+='?';
                    Num_Que.push(Number);
                    Number=0;
                    Pow=10;
                    Point_Flag=0;
                }
            }
            else if(Init_Equal[i]=='(')
            {
                Signal.push(Init_Equal[i]);
            }
            else if(Init_Equal[i]==')')
            {
                while(Signal.top()!='(')
                {
                    Equal+=Signal.top();
                    Signal.pop();
                }
                Signal.pop();
            }
            else if(Init_Equal[i]=='+'||Init_Equal[i]=='-')
            {
                while(!Signal.empty()&&Signal.top()!='(')
                {
                    Equal+=Signal.top();
                    Signal.pop();
                }
                Signal.push(Init_Equal[i]);
            }
            else if(Init_Equal[i]=='*'||Init_Equal[i]=='/')
            {
                while(!Signal.empty()&&Signal.top()!='('&&(Signal.top()=='*'||Signal.top()=='/'))		//乘法和除法优先级一致
                {
                    Equal+=Signal.top();
                    Signal.pop();
                }
                Signal.push(Init_Equal[i]);
            }
            else
                continue;
            i++;
        }
    
        while(!Signal.empty())
        {
            Equal+=Signal.top();
            Signal.pop();
        }
    }
    
    
    double Get_Sum(string& Equal,queue<double> Num_Que)
    {
        stack<double> Data;
    
        for(int i=0;i<Equal.length();i++)
        {
            double Val1,Val2;
            if(Equal[i]=='?')
            {
                Data.push(Num_Que.front());
                Num_Que.pop();
            }
            else if(Equal[i]=='+')
            {
                Val1=Data.top();
                Data.pop();
                Val2=Data.top();
                Data.pop();
                Data.push(Val1+Val2);
            }
            else if(Equal[i]=='-')
            {
                Val1=Data.top();
                Data.pop();
                Val2=Data.top();
                Data.pop();
                Data.push(Val2-Val1);
            }
            else if(Equal[i]=='*')
            {
                Val1=Data.top();
                Data.pop();
                Val2=Data.top();
                Data.pop();
                Data.push(Val1*Val2);
            }
            else if(Equal[i]=='/')
            {
                Val1=Data.top();
                Data.pop();
                Val2=Data.top();
                Data.pop();
                Data.push(Val2/Val1);
            }
            else
                continue;
    
        }
        return Data.top();
    }
    int main()
    {
        int t;
        cin>>t;
        while(t--)
        {
            string Init_Equal;
            string Equal;
            queue<double> Num_Que;
    
            cin>>Init_Equal;
            Tranfer_Equal(Init_Equal,Equal,Num_Que);
    
            /*for(int i=0;i<Equal.length();i++)
            {
                if(Equal[i]=='?')
                {
                    cout<<Num_Que.front();
                    Num_Que.pop();
                }
                else
                    cout<<Equal[i];
            }
            cout<<endl;*/
    
            double Res=Get_Sum(Equal,Num_Que);
            cout<<fixed<<setprecision(4)<<Res<<endl;
        }
        return 0;
    }

[Link 1]: https://blog.csdn.net/SZU_Crayon/article/details/79084045
[-OpenJudge]: https://blog.csdn.net/SZU_Crayon/article/details/81416656