P1022 计算器的改良

P1022 计算器的改良

#include <bits/stdc++.h>
using namespace std;


int cnt(vector<int>nums){
    int ans=0;
    for (int i = 0; i <nums.size() ; ++i) {
        ans+=nums[i];
    }
    return ans;
}


//偶数下降，奇数上升
int main(){
    int num=0,zf=1;
    vector<int>a,b;
    char x;
    string str,str1,str2;
    cin>>str;
    auto pos=str.find('=');
    str1=str.substr(0,pos);
    str2=str.substr(pos+1);
    //处理等号左边的式子
    for (int i = 0; i <str1.length() ; ++i) {
        //cout<<str1[i];
            if (str1[i]>='0'&&str1[i]<='9'){
                num*=10;
                num+=str1[i]-'0';
            }else if (str1[i]=='-'){
                b.push_back(zf*num);
                num=0;
                zf=-1;
                if (str1[i+1]>='a'&&str1[i]<='z'){
                    x=str[i+1];
                    a.push_back(-1);
                    zf=1,num=0;
                }
            }
            else if (str1[i]>='a'&&str1[i]<='z'){
                x=str1[i];
                if (num!=0)
                    a.push_back(zf*num);
                else
                    a.push_back(1);
                zf=1,num=0;
            } else
                b.push_back(zf*num),zf=1,num=0;
    }
    if (num!=0)
        b.push_back(zf*num);
    //处理等号右边的式子
    num=0,zf=1;
    for (int i = 0; i <str2.length() ; ++i) {
        if (str2[i]>='0'&&str2[i]<='9'){
            num*=10;
            num+=str2[i]-'0';
        }else if (str2[i]=='-'){
            b.push_back(-1*zf*num);
            zf=-1;
            if (str2[i+1]>='a'&&str2[i]<='z'){
                x=str2[i+1];
                a.push_back(1);
                zf=1,num=0;
            }
            num=0;
        }
        else if (str2[i]>='a'&&str2[i]<='z'){
            x=str2[i];
            if (num!=0)
                a.push_back(-1*zf*num);
            zf=1,num=0;
        } else
            b.push_back(-1*zf*num),zf=1,num=0;
    }
    b.push_back(-1*zf*num);
    double ans=(double)(cnt(b))*-1.0/(double)(cnt(a));
    if (ans==-0)
        ans=0;
    printf("%c=%.3lf",x,ans);
    return 0;
}```