（水题）洛谷 - P1022 - 计算器的改良

https://www.luogu.org/problemnew/show/P1022

服了，居然还有+0.000和-0.000的不同，真的服了。

#include<bits/stdc++.h>

using namespace std;

#define ll long long

//a1x+b1=a2x+b2

double a1,b1,a2,b2;

int main(){

    string s;

    string s1;

    string s2;

    while(cin>>s){

        int n=s.length();

        char c;

        for(int i=;i<n;i++){

            if(s[i]=='='){

                s1=s.substr(,i);

                s2=s.substr(i+,n);

                break;

            }

        }

        int n1=s1.length();

        int n2=s2.length();

        //cout<<s1<<" "<<s2<<endl;

        double cur=;

        double flag=;

        for(int i=;i<n1;i++){

            if(s1[i]=='-'){

                b1+=flag*cur;

                flag=-;

                cur=;

            }

            else if(s1[i]=='+'){

                b1+=flag*cur;

                flag=+;

                cur=;

            }

            else if(isalpha(s1[i])){

                c=s1[i];

                if(cur==)

                    cur=;

                a1+=flag*cur;

                cur=;

            }

            else{

                cur*=;

                cur+=(s1[i]-'');

            }

        }

        b1+=flag*cur;

        flag=;

        cur=;

        //cout<<a1<<" "<<b1<<endl;

        for(int i=;i<n2;i++){

            if(s2[i]=='-'){

                b2+=flag*cur;

                flag=-;

                cur=;

            }

            else if(s2[i]=='+'){

                b2+=flag*cur;

                flag=+;

                cur=;

            }

            else if(isalpha(s2[i])){

                c=s2[i];

                if(cur==)

                    cur=;

                a2+=flag*cur;

                flag=+;

                cur=;

            }

            else{

                cur*=;

                cur+=(s2[i]-'');

            }

        }

        b2+=flag*cur;

        flag=;

        cur=;

        //cout<<a2<<" "<<b2<<endl;

        //ax=b

        double a=a1-a2;

        double b=b2-b1;

        double ans=b/a;

        if(fabs(ans)<1e-)

            ans=;

        printf("%c=%.3f\n",c,ans);

    }

}