刚刚用洛谷IDE跑了一下，回车的问题解决了，麻烦点进来的大佬看一眼这份32分代码哪里出错了QwQ
```cpp
#include<iostream>
#include<cstdio>
#include<string>
#include<cstring>
using namespace std;
/*
20+3x=-18
x=-12.667
*/
string str;
double ans=0,c,v;//常数，字母系数
int mark;
int len=0,tmp=0,neg=1;
bool foundIt=true;
int main(){
// freopen("in.txt","r",stdin);
getline(cin,str);
len=str.length();
tmp=0;
for(int i=0;i<len-1;i++){
if(str[i]=='-'){
if(foundIt) neg=0-neg;
tmp*=neg;
neg=-1;
c+=tmp;
tmp=0;
}else{
if(str[i]=='+'){
if(foundIt) neg=0-neg;
tmp*=neg;
neg=1;
c+=tmp;
tmp=0;
}else{
if(str[i]>='0'&&str[i]<='9'){
tmp=tmp*10+str[i]-'0';
}else{
if(str[i]=='='){
foundIt=false;
tmp*=neg;
neg=1;
c+=tmp;
tmp=0;
}else{
if(str[i]=='\n') continue;
mark=str[i]-'a';
if(!foundIt) neg=0-neg;
tmp*=neg;
neg=1;
v+=tmp;
tmp=0;
}
}
}
}
}
if(tmp){
tmp*=neg;
c+=tmp;
}
ans=c/v;
// cout<<c<<' '<<v<<endl;
printf("%c=%.3lf",mark+'a',ans);
return 0;
}
```
by entity @ 2020-11-05 23:27:19