PAT 1108 Finding Average

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<iostream> //sscanf,sprintf的运用

#include<string.h>

using namespace std;

int main(){

	char a[50], b[50];

	double sum, temp;

	int N, cnt=0;

	cin>>N;

	for(int i=0; i<N; i++){

		scanf("%s",a);

		sscanf(a,"%lf",&temp);

		sprintf(b,"%.2lf",temp);

		int flag=0;

		for(int j=0; j<strlen(a); j++){

			if(a[j]!=b[j])

				flag=1;

		}

		 if(flag || temp < -1000 || temp > 1000) {

            printf("ERROR: %s is not a legal number\n", a);

            continue;

        } else {

            sum += temp;

            cnt++;

        }

	}

	if(cnt == 1) {

        printf("The average of 1 number is %.2lf", sum);

    } else if(cnt > 1) {

        printf("The average of %d numbers is %.2lf", cnt, sum / cnt);

    } else {

        printf("The average of 0 numbers is Undefined");

    }

    return 0;

}

巴特西

PAT 1108 Finding Average

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