# 1108. Finding Average (20)

xiaoxiao2021-02-28  9

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

#include<stdio.h> #include<stdlib.h> #include<string.h> int main() { int i,j,n,m,k,t,l,p,x,num=0,digit=0; char str[100]; double sum=0; scanf("%d",&n); for(i=0;i<n;i++) { scanf("%s",str); l=strlen(str); k=0; t=0; p=0; for(j=0;j<l;j++) { if(j==0) { if(str[j]=='-'||str[j]=='+') { k++; } else if(str[j]=='.'||(str[j]>='0'&&str[j]<='9')) { k++; if(str[j]=='.') { p++; for(x=j;x<l;x++) { if(str[x]>='0'&&str[x]<='9') { t++; digit++; } } break; } else { digit++; } } } else { if(str[j]>='0'&&str[j]<='9') { k++; digit++; } else if(str[j]=='.') { p++; k++; for(x=j;x<l;x++) { if(str[x]>='0'&&str[x]<='9') { t++; digit++; } } break; } } } if(p<=1&&k+t==l&&digit!=0) { double tmp=atof(str); if(tmp>=-1000&&tmp<=1000&&t<=2) { sum=sum+tmp; num++; } else { printf("ERROR: %s is not a legal number\n",str); } } else { printf("ERROR: %s is not a legal number\n",str); } } if(num==1) printf("The average of 1 number is %.2lf\n",sum); else if(num>1) printf("The average of %d numbers is %.2lf\n",num,sum/num); else printf("The average of 0 numbers is Undefined\n"); return 0; }