Molar mass UVA - 1586

#include<iostream>
#include<string>
#include<iomanip>
using namespace std;
int main()
{
    int N;
    cin>>N;
    while(N--)
    {
        double numC=0,numH=0,numN=0,numO=0;
        string s;
        cin>>s;
        int len = s.length();
        for(int i=0;i<len;i++){
            if(s[i]=='C')numC++;
            if(s[i]=='H')numH++;
            if(s[i]=='O')numO++;
            if(s[i]=='N')numN++;
            if(s[i]>='1'&&s[i]<='9'){
                int tmp,flag=0;
                    if(s[i+1]>='1'&&s[i+1]<='9'){
                     tmp = (s[i]-'0')*10+s[i+1]-'0'-1;
                     flag=1;
                    }
                     else
                     tmp=s[i]-'0'-1;
            if(s[i-1]=='C')numC+=tmp;
            if(s[i-1]=='H')numH+=tmp;
            if(s[i-1]=='O')numO+=tmp;
            if(s[i-1]=='N')numN+=tmp;
            if(flag==1)i++;
            }
        }
        double sum = numC*12.01+numH*1.008+numN*14.01+numO*16.00;
        cout<<fixed<<setprecision(3)<<sum<<endl;
    }
    return 0;
}

这个题目我能想到的就是这些啦，思路还是挺简单的，写的程序可能有点繁琐。