1108 Finding Average

Statement

Metadata

作者: CHEN, Yue
单位: 浙江大学
代码长度限制: 16 KB
时间限制: 400 ms
内存限制: 64 MB

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 $N$ ( $\le 100$ ). 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

Last update: May 4, 2022