UVA1586 分子量 2020-04-13

题目：https://vjudge.net/problem/UVA-1586

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

int main(){
    int num = 0;
    cin >> num;

    map<char, double> map;
    map['C'] = 12.01;
    map['H'] = 1.008;
    map['O']= 16.00;
    map['N'] = 14.01;

    while (num--)
    {
        string s;
        cin >> s;
        int len = s.size();
        double mass = 0.0;
        for (int i = 0; i < len;i++){
            if(isdigit(s[i]))
                continue;
            double a = map[s[i]];
            int cn = 1;
            if(i+2<len && isdigit(s[i+1]) && isdigit(s[i+2])){  //如果有两个数字，就读取两个数字
                cn = (s[i + 1] - '0') * 10 + (s[i + 2] - '0');
            }else if(i+1<len && isdigit(s[i+1])){  //一个数字就读取一个，不要用while，因为限制了下标范围2-99
                cn = s[i + 1] - '0';
            }
           
            mass += a*cn;
        }
        cout << mass <<endl;
    }
   // system("pause");
    return 0;
}

bool isdigit（char ch）判断字符是否为数字。
更多cctype函数