1054 求平均值 （20 分）

#include<iostream>
#include<cstdio>
#include<string.h>
using namespace std;
int main(){
    int n,cnt=0;
    double tmp,sum=0.0;
    char a[50],b[50];
    cin>>n;
    for(int i=0;i<n;i++){
        scanf("%s",a);
        sscanf(a,"%lf",&tmp);
        sprintf(b,"%.2f",tmp);
        int flag=0;
        for(int j=0;j<strlen(a);j++){
        //    cout<<"a[j]="<<a[j]<<"     b[j]="<<b[j]<<endl;
            if(a[j]!=b[j]){
                flag=1;
                break;
            }
        }
            
        if(flag||tmp<-1000||tmp>1000){
            printf("ERROR: %s is not a legal number\n", a);
            continue;
        }else {
            sum+=tmp;
            cnt++;
        }
    }
    if(cnt==1)
        printf("The average of 1 number is %.2f", sum);
    else if(cnt > 1)
        printf("The average of %d numbers is %.2f", cnt, sum / cnt);
    else
        printf("The average of 0 numbers is Undefined");

    return 0;

}