PAT甲级——A1108 Finding Average【20】
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 [−] 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 (≤). 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 <vector> 3 using namespace std; 4 #define inf 1000 5 double sum = 0.0, number; 6 int n, nums = 0; 7 int main() 8 { 9 cin >> n; 10 char str1[100], str2[100]; 11 while (n--) 12 { 13 cin >> str1; 14 bool flag = true; 15 sscanf(str1, "%lf", &number);//将字符转换为浮点数值 16 sprintf(str2, "%0.2f", number);//按要求输出 17 for (int i = 0; str1[i] != '\0'&& flag; ++i) 18 if (str1[i] != str2[i]) 19 flag = false; 20 if (!flag || number<-inf || number>inf) 21 cout << "ERROR: " << str1 << " is not a legal number" << endl; 22 else 23 { 24 nums++; 25 sum += number; 26 } 27 } 28 cout << "The average of " << nums << (nums == 1 ? " number is " : " numbers is "); 29 if (nums == 0) 30 cout << "Undefined" << endl; 31 else 32 printf("%0.2f\n", sum / nums); 33 return 0; 34 }