1586 - Molar mass （UVA）

题目链接如下：

Online Judge

我的代码如下：

#include 
#include 
#include 
const int maxN = 81;

int T, temp, coef;
double ans;
double w[] = {12.01, 1.008, 16.00, 14.01};
char a[81];

int main(){
    scanf("%d", &T);
    while(T--){
        scanf("%s", a);
        ans = 0;
        for(int i = 0; i < strlen(a); ++i){
            if(a[i] == 'C'){
                temp = 0;
            } else if(a[i] == 'H'){
                temp = 1;
            } else if(a[i] == 'O'){
                temp = 2;
            } else{
                temp = 3;
            }
            if(isalpha(a[i + 1]) || a[i + 1] == '\0'){
                ans += w[temp];
                continue;
            }
            coef = 0;
            while(isdigit(a[i + 1])){
                i++;
                coef = coef * 10 + (a[i] - '0');
            }
            ans += coef * w[temp];
        }
        printf("%.3f\n", ans);
    }
    return 0;
}