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 [−] 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 (≤). 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>
#include<string>

using namespace std;

bool judge(string t)
{
    bool reflag=false;
    int dotloca=-1;
    for(int i=0;i<t.size();i++)
    {
        if((t[i]>='0'&&t[i]<='9')||t[i]=='.'||t[i]=='-')
        {
            if(t[i]=='-'&&i!=0) return false;
        //    if(t[i]=='.'&&i==0) return false;      //.在最前数据例子中暂无 
            if(t[i]=='.'&&dotloca!=-1) return false;     //.在最后算对 故不要排除 
            if(t[i]=='.'&&dotloca==-1) dotloca=i;
            if(dotloca!=-1&&i>dotloca+2) return false;
        } 
        else
        {
             return false;
        }
    
    }
    return true;
}
double intonum(string t)
{
    double result=0;
    double fh=1.0;
    int start=0;
    int dotwz=-1;
    if(t[0]=='-')  
    {
        fh=-1.0;    
        start=1;
    }
    for(int i=start;i<t.size();i++)
    {
        if(t[i]=='.') dotwz=i;
    }

    if(dotwz!=-1)
    {
        for(int j=start;j<dotwz;j++)
        {
                int n=t[j]-'0';
                result=result*10;
                result+=n;
        }
        double temp=0;
        for(int j=t.size()-1;j>=dotwz+1;j--)
        {
            int n=t[j]-'0';
            temp+=n;
            temp=temp*0.1;
        }
        result+=temp;
    }
    else
    {
        for(int j=start;j<t.size();j++)
        {
            int n=t[j]-'0';
            result=result*10;
            result+=n;
        }
    }
    return (result*fh);
}
int main()
{
    int num;
    cin>>num;
    int count=0;
    double sum=0;
    for(int i=0;i<num;i++)
    {
        string temp;
        cin>>temp;
        bool flag=judge(temp);
        if(flag==false)
        {
            cout<<"ERROR: "<<temp<<" is not a legal number"<<endl;
        }
        else
        {
            double mynum=intonum(temp);
            if(mynum<=1000&&mynum>=-1000)
            {
                sum+=mynum;
                count++;
            }
            else
            {
                cout<<"ERROR: "<<temp<<" is not a legal number"<<endl;
            }
            
        }
    }
    double result=sum/count;
    if(count==0) printf("The average of 0 numbers is Undefined");
    else if(count==1) printf("The average of %d number is %.2f",count,result); //注意s 
    else printf("The average of %d numbers is %.2f",count,result);
 }