文章目录

• • 一、门牌制作
  • 二、分数
  • 三、蛇形填数
  • 六、成绩分析
  • 七、回文日期
  • 八、字串分值

一、门牌制作

package _2020_Java_A;
import java.util.*;
public class _01门牌 {

	private static int ans;

	public static void main(String[] args) {
		// TODO Auto-generated method stub
		for(int i=1;i<=2020;i++) {
			ans += num(i);
		}
		System.out.print(ans);
	}

	private static int num(int n) {
		// TODO Auto-generated method stub
		int ans = 0;
		while(n!=0) {
			int m = n%10;//取最低位
			if(m==2) ans ++;
			n = n/10;
		}
		return ans;
	}
//624
}

二、分数

package _2020_Java_A;
import java.util.*;
public class _02分数 {

	private static int ans;

	public static void main(String[] args) {
		// TODO Auto-generated method stub
		for(int i=1;i<=2020;i++) {
			for(int j=1;j<=2020;j++) {
				if(gcd(i,j)==1) ans ++;
			}
		}
		System.out.print(ans);
	}

	private static int gcd(int m, int n) {
		// TODO Auto-generated method stub
		if(m==0)return n;
		else return gcd(n%m,m);
	}
//2481215
}

三、蛇形填数

package _2020_Java_A;

public class _03C填数 {

	public static void main(String[] args) {
		// TODO Auto-generated method stub
		int n = 20;
		int ans = 0;
		for(int i=1;i<=2*n-2;i++) {
			//前面的2n-2长
			ans += i;
		}
		ans += n;
		System.out.print(ans);
	}
//761
}

六、成绩分析

package _2020_Java_A;
import java.util.*;
public class _06F成绩 {

	public static void main(String[] args) {
		// TODO Auto-generated method stub
		Scanner sc = new Scanner(System.in);
		int n  = sc.nextInt();
		int [] s = new int[n];//存放成绩
		float avg;
		float total = 0;
		int max = Integer.MIN_VALUE;
		int min = Integer.MAX_VALUE;
		for(int i=0;i<n;i++) {
			s[i] = sc.nextInt();
			if(s[i]>max) max = s[i];
			if(s[i]<min) min = s[i];
			total += s[i];
		}
		avg = total/n;
		System.out.println(max);
		System.out.println(min);
		System.out.printf("%.2f\n",avg);
		sc.close();
	}

}

七、回文日期

package _2020_Java_A;
import java.util.*;
import java.text.*;
public class _07G回文日期 {

	public static void main(String[] args) {
		// TODO Auto-generated method stub
		Scanner sc = new Scanner(System.in);
		String str = sc.next();
		Calendar c = Calendar.getInstance();
		int year = Integer.parseInt(str.substring(0, 4));
		int month = Integer.parseInt(str.substring(4, 6));
		int date = Integer.parseInt(str.substring(6, 8));
		c.set(year, month,date);
		boolean flag = false;
		SimpleDateFormat sdf = new SimpleDateFormat("yyyyMMdd");
		while(true) {
			c.add(Calendar.DAY_OF_YEAR, 1);
			String ans = sdf.format(c.getTime());
			if(huiwen(ans)) {
				if(!flag) {
					System.out.println(ans);
					flag = true;
				}
				if(AB(ans)) {
					System.out.println(ans);
					break;
				}
			}
		}
		sc.close();
	}

	private static boolean AB(String ans) {
		// TODO Auto-generated method stub
		return ans.charAt(0)==ans.charAt(2)&&ans.charAt(1)==ans.charAt(3);
	}

	private static boolean huiwen(String ans) {
		// TODO Auto-generated method stub
		StringBuffer res = new StringBuffer(ans);
		return ans.equals(res.reverse().toString());
	}

}

八、字串分值

package _2020_Java_A;
import java.util.*;
public class _08H字串分值 {

	public static void main(String[] args) {
		// TODO Auto-generated method stub
		Scanner sc = new Scanner(System.in);
		String str = sc.next();
		int ans = f(str);
		System.out.print(ans);
		sc.close();
	}

	private static int f(String str) {
		// TODO Auto-generated method stub
		char[] ch = str.toCharArray();
		int n = ch.length;
		int res = 0;
		int i,j,k;
		for (i = 0; i < n; i++) {
			for (j = i - 1; j >= 0; j--) {
				if (ch[j] == ch[i])
					break;
			}
			for (k = i + 1; k < n; k++) {
				if (ch[k] == ch[i])
					break;
			}
			res += (k-i)*(i-j);
		}
		return res;
	}

}

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