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
#include<bits/stdc++.h>
using namespace std;
double temp;
bool isnum(char str[]){
temp = 0;
int size = strlen(str);
bool point = false;
int pointindex = 0;
for(int i = 0; i < size; i++){
if(str[i] == '-'){
if(i == 0 )
continue;
}
if(str[i] >= '0' && str[i] <= '9'){
if(!point)
temp = temp * 10 + str[i] - '0';
else
temp += (str[i] - '0') * pow(10, pointindex - i);
}
else if(str[i] == '.'){
if(point)
return false;
pointindex = i;
if(size - 1 - pointindex > 2)
return false;
point = true;
}
else
return false;
}
if(str[0] == '-')
temp *= -1;
if(temp <= 1000 && temp >= -1000)
return true;
return false;
}
int main(){
int n;
scanf("%d", &n);
char str[100];
double sum = 0, num = 0;
for(int i = 0; i < n; i++){
scanf("%s", &str);
if(isnum(str)){
num++;
sum += temp;
}
else
printf("ERROR: %s is not a legal number\n", str);
}
if(num == 0)
printf("The average of %d numbers is Undefined", int(num));
else if(num == 1)
printf("The average of %d number is %.2lf", int(num), sum);
else
printf("The average of %d numbers is %.2lf", int(num), sum / num);
return 0;
}