A1108. 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<cstdio>

 #include<iostream>

 #include<string.h>

 using namespace std;

 char num[];

 const double INF = 100000000.0;

 double prase_(char num[]){

     int len = strlen(num);

     int pos = -, cnt = ;

     int tag = ;

     for(int i = ; num[i] != '\0'; i++){

         if(!(num[i] >= '' && num[i] <= '' || num[i] == '.' || num[i] == '-')){

             return INF;

         }

         if(num[i] == '.')

             cnt++;

         if(cnt > )

             return INF;

     }

     if(num[] == '-')

         tag = ;

     for(pos = ; num[pos] != '.' && num[pos] != '\0'; pos++);

     int P = , ansL = , ansR = ;

     if(pos == '\0'){

         for(int i = len - ; i >= tag; i--){

             ansL += (num[i] - '') * P;

             P *= ;

         }

         if(tag == )

             return ansL * -1.0;

         else return ansL * 1.0;

     }else{

         if(len - pos -  > )

             return INF;

         P = ; ansL = ;

         for(int i = pos - ; i >= tag; i--){

             ansL += (num[i] - '') * P;

             P *= ;

         }

         P = ; ansR = ;

         for(int i = len - ; i > pos; i--){

             ansR += (num[i] - '') * P;

             P *= ;

         }

         double temp = ansR * 1.0;

         for(int i = ; i < len - pos - ; i++){

             temp *= 0.1;

         }

         if(tag == )

             return ((double)ansL + temp) * -1.0;

         else return (double)ansL + temp;

     }

 }

 int main(){

     int N, cnt = ;

     double sum = , temp = ;

     scanf("%d", &N);

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

         scanf("%s", num);

         temp = prase_(num);

         if(temp > 1000.0 || temp < -1000.0){

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

         }else{

             sum += temp;

             cnt++;

         }

     }

     if(cnt > ){

         double prt = sum / (double)cnt;

         printf("The average of %d numbers is %.2f\n", cnt, prt);

     }else if (cnt == ){

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

     }else if(cnt == ){

         double prt = sum / (double)cnt;

         printf("The average of %d number is %.2f\n", cnt, prt);

     }

     cin >> N;

     return ;

 }

巴特西

A1108. Finding Average

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