PAT乙级 1012 数字分类

#include<iostream>
#include<algorithm>
using namespace std;
int n;
int main()
{
    int a1=0,a2=0,cnt2=0,a3=0,sum4=0,cnt4=0,a5=0;
    double a4=0.0;
    int b=1;
    //易错点，如果将a1,a2,a3等等是否为0作为判断N,将会造成错误的情况，如果算出a1,a2等等本身是0会造成歧义
    //所以另开count1,count2等等作为判断条件 
    int count1 = 0, count2 = 0, count3 = 0, count4 = 0, count5 = 0;
    cin>>n;
    for(int i = 0; i<n; i++)
    {
        int x; cin>>x;
        if(x%5==0 && x%2==0)
        {
            count1++;a1+=x;
        }
        if(x%5==1)
        {
            count2++;
            a2+=b*x;
            b=-b;
        }
        if(x%5==2)
        {
            count3++;a3++;
        }
        if(x%5==3)
        {
            count4++;
            cnt4++;
            sum4+=x;
        }
        if(x%5==4)
        {
            count5++;
            a5=a5>x?a5:x;
        }
    }
    if(count1)cout<<a1<<" ";
    else cout<<"N ";

    if(count2)cout<<a2<<" ";
    else cout<<"N ";

    if(count3)cout<<a3<<" ";
    else cout<<"N ";

    if(count4) printf("%.1lf ",(double)sum4/cnt4);
    else cout<<"N ";

    if(count5)cout<<a5;
    else cout<<"N";
    return 0;
}