牛客网：数字分类

题目：

A1 = 能被5整除的数字中所有偶数的和；

A2 = 将被5除后余1的数字按给出顺序进行交错求和，即计算n1-n2+n3-n4…；

A3 = 被5除后余2的数字的个数；

A4 = 被5除后余3的数字的平均数，精确到小数点后1位；

A5 = 被5除后余4的数字中最大数字。
源码：

import java.text.DecimalFormat;
import java.util.*;
public class Main {
    public static void main(String[] args) {
        Scanner in = new Scanner(System.in);
            int N = in.nextInt();
            int sum = 0;
            int sum2 = 0;
            int number = 0;
            int eql = 0;
            int numEql = 0;
            int max = 0;
            boolean tag = true;
            for (int i = 0; i < N; i++) {
                int tmp = in.nextInt();
                if (tmp % 5 == 0 && tmp % 2 ==0) {
                    sum += tmp;
                } else if (tmp % 5 == 1) {
                    if (tag) {
                        sum2 += tmp;
                        tag = false;
                    } else {
                        sum2 -= tmp;
                        tag = true;
                    }
                } else if (tmp % 5 == 2) {
                    number++;
                } else if (tmp % 5 == 3) {
                    numEql++;
                    eql += tmp;
                } else if (tmp % 5 == 4) {
                    max = max > tmp ? max : tmp;
                }
            }
            if (sum == 0) {
                System.out.print("N" + " ");
            } else {
                System.out.print(sum + " ");
            }
            if (sum2 == 0) {
                System.out.print("N" + " ");
            } else {
                System.out.print(sum2 + " ");
            }
            if (number == 0) {
                System.out.print("N" + " ");
            } else {
                System.out.print(number + " ");
            }
            if (numEql == 0) {
                System.out.print("N" + " ");
            } else {
                String res = null;
                res = new DecimalFormat("0.0").format(eql*1.0 / numEql);
                System.out.print(res + " ");
            }
            if (max == 0) {
                System.out.print("N");
            } else {
                System.out.print(max);
            }
        }
}