ACM_UVA1586

</pre><p><span style="background-color: rgb(240, 240, 240);">#include<iostream></span></p><p><pre name="code" class="cpp">using namespace std;#include<string.h>int main(){char s[30];scanf("%s", s);double sum = 0.0;double w;int len = strlen(s);//printf("%d", '6' - '0');for (int i = 0; i < len; ){switch (s[i]){case'C': w = 12.01;break;case'H': w = 1.008;break;case'O': w = 16.00;break;case'N': w = 14.01;break;}if (i + 1 < len && s[i + 1] <= '9'){int tail = i + 1;while (tail < len && (s[tail] <= '9'))tail++;int v = tail - 1;int n = 0;int y = 1;while (v != i){n += ((s[v] - '0') * y);y *= 10;v--;}sum += (w * n);i = tail;}else{sum += w;i++;}}printf("%.3f", sum);}

总结：

1.当要使用i+1时，边界处要对其经常判定

2.注意变量的作用域。