1108 Finding Average（20 分）
The basic task is simple: given N real numbers, you are supposed to calculate their average. But what makes it complicated is that some of the input numbers might not be legal. A legal input is a real number in [?1000,1000] and is accurate up to no more than 2 decimal places. When you calculate the average, those illegal numbers must not be counted in.
Input Specification:
Each input file contains one test case. For each case, the first line gives a positive integer N (≤100). Then N numbers are given in the next line, separated by one space.
Output Specification:
For each illegal input number, print in a line ERROR: X is not a legal number where X is the input. Then finally print in a line the result: The average of K numbers is Y where K is the number of legal inputs and Y is their average, accurate to 2 decimal places. In case the average cannot be calculated, output Undefined instead of Y. In case K is only 1, output The average of 1 number is Y instead.
Sample Input 1:
7
5 -3.2 aaa 9999 2.3.4 7.123 2.35
Sample Output 1:
ERROR: aaa is not a legal number
ERROR: 9999 is not a legal number
ERROR: 2.3.4 is not a legal number
ERROR: 7.123 is not a legal number
The average of 3 numbers is 1.38
Sample Input 2:
2
aaa -9999
Sample Output 2:
ERROR: aaa is not a legal number
ERROR: -9999 is not a legal number
The average of 0 numbers is Undefined 1 #include <iostream>
2 #include <algorithm>
3 #include <cstdio>
4 #include <cstring>
5 #include <string>
6 #include <map>
7 #include <stack>
8 #include <vector>
9 #include <queue>
10 #include <set>
11 #define LL long long
12 #define INF 0x3f3f3f3f
13 using namespace std;
14 const int MAX = 1e3;
15
16 int n, cnt = 0;
17 double ans = 0.0;
18 char s[MAX], notlegal[105][MAX];
19
20 bool my_is_ans()
21 {
22 int len = strlen(s), my_cnt = 0;
23 // if (s[0] == ‘.‘ || s[len - 1] == ‘.‘) return false;
24 for (int i = 0; i < len; ++ i)
25 {
26 if (isalpha(s[i])) return false;
27 if (s[i] == ‘.‘)
28 {
29 my_cnt ++;
30 if (my_cnt >= 2) return false;
31 if (i <= len - 4) return false;
32 }
33 }
34 return true;
35 }
36
37 int main()
38 {
39 // freopen("Date1.txt", "r", stdin);
40 scanf("%d", &n);
41 for (int i = 1; i <= n; ++ i)
42 {
43 scanf("%s", &s);
44 double d;
45
46 if (!my_is_ans() || sscanf(s, "%lf", &d)!= 1 || d < -1000 || d > 1000)
47 {
48 strcpy(notlegal[cnt ++], s);
49 continue;
50 }
51 ans += d;
52 }
53
54 for (int i = 0; i < cnt; ++ i)
55 printf("ERROR: %s is not a legal number\n", notlegal[i]);
56 if (n - cnt == 0)
57 printf("The average of 0 numbers is Undefined\n");
58 else if (n - cnt == 1)
59 printf("The average of 1 number is %.2lf\n", ans);
60 else
61 printf("The average of %d numbers is %.2lf\n", n - cnt, ans / (n - cnt));
62 return 0;
63 }
原文地址：https://www.cnblogs.com/GetcharZp/p/9593742.html