PAT_B1002数字分类

#include<stdio.h>
#include<iostream>
using namespace std;
int main(){
    int a1=0,a2=0,a3=0,a5=0;
    double a4=0;
    int a4num=0;
    int n;
    cin>>n;
    int x,i=1;
    while(n--){
        cin>>x;
        switch(x%5){
            case 0:
                if(x%2==0){
                    a1+=x;
                }
                break;
            case 1:
                a2+=(i*x);i=-i;//交替求和
                break;
            case 2:
                a3++;
                break;
            case 3:
                a4+=(double)x;
                a4num++;
                break;
            case 4:
                if(x>a5)
                a5=x;
                break;
        }
    }
    (a1>0)?(cout<<a1<<" "):(cout<<"N"<<" ");
    (a2!=0)?(cout<<a2<<" "):(cout<<"N"<<" ");
    (a3>0)?(cout<<a3<<" "):(cout<<"N"<<" ");
    (a4>0)?(printf("%.1f ",a4/(double)a4num)):(printf("N "));
    (a5>0)?(cout<<a5):(cout<<"N");
    return 0;
}