C3-UVa1586-Molar mass

平台:

UVa Online Judge

題號:

1586 - Molar mass

題目連結:

https://onlinejudge.org/index.php?option=com_onlinejudge&Itemid=8&category=448&page=show_problem&problem=4461

題目說明:

给出一种物质的分子式(不带括号),求分子量。本题中的分子式只包含4种原子,分别为C, H, O, N,原子量分别为12.01, 1.008, 16.00, 14.01(单位:g/mol)。例如,C6H5OH的分子量为94.108g/mol。

範例輸入:

4
C
C6H5OH
NH2CH2COOH
C12H22O11

範例輸出:

12.010
94.108
75.070
342.296

解題方法:

用while循环取数字,组成n位数。

程式碼:

 1 #include 
 2 #include 
 3 #include 
 4 
 5 const int MAXN = 85;
 6 double    q['Z'] = { 0 };
 7 
 8 void setStandard() {
 9     q['C'] = 12.01;
10     q['H'] = 1.008;
11     q['O'] = 16.00;
12     q['N'] = 14.01;
13 }
14 
15 int main() {
16     setStandard();
17     int T = 0;
18     scanf("%d", &T);
19     while (T--) {
20         char formula[MAXN] = "";
21         scanf("%s", formula);
22         int num = 0;
23         double sta = 0.0, sum = 0.0;
24         for (int i = 0; i < strlen(formula); ) {
25             if (isalpha(formula[i])) {
26                 sta = q[formula[i++]];
27                 while (isdigit(formula[i])) {
28                     num = num * 10 + formula[i] - '0';
29                     i++;
30                 }
31                 if (num == 0) {
32                     num = 1;
33                 }
34                 sum += sta * num;
35                 num = 0;
36             }
37 
38         }
39         printf("%.3lf\n", sum);
40     }
41 }

 

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