UVA - 1586 Molar mass

UVA - 1586

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#include"stdio.h"
#include"ctype.h"
#include"string.h"
double sum;
int len;
char s[85];
void su(char c,int d)
{
    if (c == 'C')sum += 12.01*d;
    if (c == 'H')sum += 1.008*d;
    if (c == 'O')sum += 16.00*d;
    if (c == 'N') sum += 14.01*d;
}
int main()
{
    int t; scanf("%d", &t);
    char last, now, llast;
    getchar();
    while (t--)
    {
        scanf("%s", s);
        len = strlen(s); 
        sum = 0;
        for (int i = 1, j = 1; i <= len; ++i)
        {
            if (isupper(s[i]) || s[i] == 0)
            {
                if (j == 1)su(s[i - 1], 1);
                else if (j == 2)
                {
                    int d = s[i - 1] - '0';
                    su(s[i - 2], d);
                }
                else
                {
                    int d = (s[i - 2] - '0') * 10 + s[i - 1] - '0';
                    su(s[i - 3], d);
                }
                j = 1;
            }
            if (isdigit(s[i]))
            {
                ++j; continue;
            }
        }
        printf("%.3lf\n", sum);
    }
    return 0;
}