HDU杭电OJ经典100题2000-2099_Java版详细题解(持续更新)

今年寒假打算用Java把杭电2000-2099全部AC(现在持续更新)，如下是题目链接，之后是我的题解,全部做完后我会把所有AC的题解打包上传的

题号	题名	题号	题名
2000	ASCII码排序	2001	计算两点间的距离
2002	计算球体积	2003	求绝对值
2004	成绩转换	2005	第几天？
2006	求奇数的乘积	2007	平方和与立方和
2008	数值统计	2009	求数列的和
2010	水仙花数	2011	多项式求和
2012	素数判定	2013	蟠桃记
2014	青年歌手大奖赛_评委会打分	2015	偶数求和
2016	数据的交换输出	2017	字符串统计
2018	母牛的故事	2019	数列有序!
2020	绝对值排序	2021	发工资咯：）
2022	海选女主角	2023	求平均成绩
2024	C语言合法标识符	2025	查找最大元素
2026	首字母变大写	2027	统计元音
2028	Lowest Common Multiple Plus	2029	Palindromes _easy version
2030	汉字统计	2031	进制转换
2032	杨辉三角	2033	人见人爱A+B
2034	人见人爱A-B	2035	人见人爱A^B
2036	改革春风吹满地	2037	今年暑假不AC
2038	test	2039	三角形
2040	亲和数	2041	超级楼梯
2042	不容易系列之二	2043	密码
2044	一只小蜜蜂...	2045	不容易系列之(3)—— LELE的RPG难题
2046	骨牌铺方格	2047	阿牛的EOF牛肉串
2048	神、上帝以及老天爷	2049	不容易系列之(4)——考新郎
2050	折线分割平面	2051	Bitset
2052	Picture	2053	Switch Game
2054	A == B n	2055	An easy problem
2056	Rectangles	2057	A + B Again
2058	The sum problem	2059	龟兔赛跑
2060	Snooker	2061	Treasure the new start, freshmen!
2062	Subset sequence	2063	过山车
2064	汉诺塔III	2065	"红色病毒"问题
2066	一个人的旅行	2067	小兔的棋盘
2068	RPG的错排	2069	Coin Change
2070	Fibbonacci Number	2071	Max Num
2072	单词数	2073	无限的路
2074	叠筐	2075	A|B?
2076	夹角有多大(题目已修改,注意读题)	2077	汉诺塔IV
2078	复习时间	2079	选课时间(题目已修改,注意读题)
2080	夹角有多大II	2081	手机短号
2082	找单词	2083	简易版之最短距离
2084	数塔	2085	核反应堆
2086	A1 = n	2087	剪花布条
2088	Box of Bricks	2089	不要62
2090	算菜价	2091	空心三角形
2092	整数解	2093	考试排名
2094	产生冠军	2095	find your present (2)
2096	小明A+B	2097	Sky数
2098	分拆素数和	2099	整除的尾数

P2000.ASCII码排序

package hdu经典100题;

import java.util.Scanner;

public class P2000 {

	public static void main(String[] args) {
		// TODO Auto-generated method stub
		Scanner in = new Scanner(System.in);
		while(in.hasNext()) {
			String str = in.next();
			int a = str.charAt(0);
			int b = str.charAt(1);
			int c = str.charAt(2);
			int temp;
			if(b>a) {
				temp = a;
				a = b;
				b = temp;
				
			}
			if(c>a) {
				temp = a;
				a = c;
				c = temp;
			}
			if(c>b) {
				temp = b;
				b = c;
				c = temp;
			}
			System.out.println((char)c+" "+(char)b+" "+(char)a);
		}
	}

}

P2001.计算两点间的距离

package hdu经典100题;

import java.text.DecimalFormat;
import java.util.Scanner;

public class P2001 {

	public static void main(String[] args) {
		// TODO Auto-generated method stub
		Scanner in = new Scanner(System.in);
		while(in.hasNext()) {
			double x1 = in.nextDouble();
			double y1 = in.nextDouble();
			double x2 = in.nextDouble();
			double y2 = in.nextDouble();
			DecimalFormat decimalFormat = new DecimalFormat(".00");
			System.out.println(decimalFormat.format(Math.sqrt((x1-x2)*(x1-x2)+(y1-y2)*(y1-y2))));
		}
	}
}

P2002.计算球体积

package hdu经典100题;

import java.util.Scanner;

public class P2002 {

	public static void main(String[] args) {
		// TODO Auto-generated method stub
		Scanner in = new Scanner(System.in);
		while(in.hasNext()) {
			double r = in.nextDouble();
			System.out.printf("%.3f\n",4.0/3.0*r*r*r*3.1415927);
		}
	}
}

P2003.求绝对值

package hdu经典100题;

import java.text.DecimalFormat;
import java.util.Scanner;

public class P2003 {

	public static void main(String[] args) {
		// TODO Auto-generated method stub
		Scanner in = new Scanner(System.in);
		while(in.hasNext()) {
			double num = in.nextDouble();
			DecimalFormat decimalFormat = new DecimalFormat(".00");
			System.out.println(decimalFormat.format(Math.abs(num)));
			
		}
		
	}

}

P2004.成绩转换

package hdu经典100题;

import java.util.Scanner;

public class P2004 {

	public static void main(String[] args) {
		// TODO Auto-generated method stub
		Scanner in = new Scanner(System.in);
		while (in.hasNext()) {
			int grade = in.nextInt();
			if(grade<0 || grade>100) {
				System.out.println("Score is error!");
			}else {
				switch (grade / 10) {
				case 10:
					System.out.println("A");
					break;
				case 9:
					System.out.println("A");
					break;
				case 8:
					System.out.println("B");
					break;
				case 7:
					System.out.println("C");
					break;
				case 6:
					System.out.println("D");
					break;
				default:
					System.out.println("E");
					break;
				}
			}
		}
	}

}

P2005.第几天？

package hdu经典100题;


import java.util.Calendar;
import java.util.GregorianCalendar;
import java.util.Scanner;

public class P2005 {

	public static void main(String[] args) {
		// TODO Auto-generated method stub
		Scanner in = new Scanner(System.in);
		while(in.hasNext()) {
			String date = in.next();
			int year = Integer.valueOf(date.substring(0,4));
			int month = Integer.valueOf(date.substring(5, date.lastIndexOf('/')));
			int day = Integer.valueOf(date.substring(date.lastIndexOf('/')+1));
			Calendar calendar = new GregorianCalendar(year, month-1, day);
			System.out.println(calendar.get(Calendar.DAY_OF_YEAR));
		}
	}

}

P2006.求奇数的乘积

package hdu经典100题;

import java.util.Scanner;

public class P2006 {

	public static void main(String[] args) {
		// TODO Auto-generated method stub
		Scanner in = new Scanner(System.in);
		while(in.hasNext()) {
			int n = in.nextInt();
			int cj = 1;
			while(n!=0) {
				int num = in.nextInt();
				if(num%2!=0) {
					cj = cj * num;
				}
				n--;
			}
			System.out.println(cj);
			
		}
		
		
	}

}

P2007.平方和与立方和

package hdu经典100题;

import java.util.Scanner;

public class P2007 {
	public static void main(String[] args) {
		Scanner in = new Scanner(System.in);
		while(in.hasNext()) {
			int m = in.nextInt();
			int n = in.nextInt();
			int temp;
			if(m>n) {
				temp = m;
				m = n;
				n = temp;
			}
			int sumOu = 0;
			int sumJi = 0;
			for (int i = m; i <= n; i++) {
				if(i%2==0) {
					sumOu+=i*i;
				}else {
					sumJi+=i*i*i;
				}
			}
			System.out.println(sumOu+" "+sumJi);
		}
	}
}

P2008.数值统计

package hdu经典100题;

import java.util.Scanner;

public class P2008 {
	public static void main(String[] args) {
		Scanner in = new Scanner(System.in);
		while(in.hasNext()) {
			int n = in.nextInt();
			if(n==0) {
				break;
			}
			int amountFu = 0;
			int amountZreo = 0;
			int amountZheng = 0;
			while(n!=0) {
				double num = in.nextDouble();
				if(num==0) {
					amountZreo++;
				}else if (num<0) {
					amountFu++;
				}else {
					amountZheng++;
				}
				n--;
			}
			System.out.println(amountFu+" "+amountZreo+" "+amountZheng);
		}
		
	}
}

P2009求数列的和

package hdu经典100题;

import java.text.DecimalFormat;
import java.util.Scanner;

public class P2009 {

	public static void main(String[] args) {
		// TODO Auto-generated method stub
		Scanner in = new Scanner(System.in);
		while(in.hasNext()) {
			double n = in.nextInt();
			int m = in.nextInt()-1;
			double sum = n;
			while(m!=0) {
				sum+=Math.sqrt(n);
				n = Math.sqrt(n);
				m--;
			}
			DecimalFormat format = new DecimalFormat(".00");
			System.out.println(format.format(sum));
		}
	}

}

P2010.水仙花数

package hdu经典100题;

import java.util.ArrayList;
import java.util.Collections;
import java.util.List;
import java.util.Scanner;

public class P2010 {

	public static void main(String[] args) {
		// TODO Auto-generated method stub
		Scanner in = new Scanner(System.in);
		while(in.hasNext()) {
			int m = in.nextInt();
			int n = in.nextInt();
			List<Integer> list = new ArrayList<>();
			for (int i = m; i <=n; i++) {
				String strNum = String.valueOf(i);
				if(i==Integer.valueOf(String.valueOf(strNum.charAt(0)))*Integer.valueOf(String.valueOf(strNum.charAt(0)))*Integer.valueOf(String.valueOf(strNum.charAt(0)))
						+Integer.valueOf(String.valueOf(strNum.charAt(1)))*Integer.valueOf(String.valueOf(strNum.charAt(1)))*Integer.valueOf(String.valueOf(strNum.charAt(1)))
						+Integer.valueOf(String.valueOf(strNum.charAt(2)))*Integer.valueOf(String.valueOf(strNum.charAt(2)))*Integer.valueOf(String.valueOf(strNum.charAt(2)))
						) {
					list.add(i);
				}
			}
			if(list.size()==0) {
				System.out.println("no");
			}else {
				Collections.sort(list);
				for (int i = 0; i < list.size()-1; i++) {
					System.out.print(list.get(i)+" ");
				}
				System.out.println(list.get(list.size()-1));
			}
		}
	}

}

P2011.多项式求和

package hdu经典100题;

import java.text.DecimalFormat;
import java.util.ArrayList;
import java.util.List;
import java.util.Scanner;

public class P2011 {

	public static void main(String[] args) {
		// TODO Auto-generated method stub
		Scanner in = new Scanner(System.in);
		int m = in.nextInt();
		int nums [] = new int [m];
		for (int i = 0; i < nums.length; i++) {
			nums[i] = in.nextInt();
		}
		List<Double> list = new ArrayList<>();
		for (int i = 0; i < nums.length; i++) {
			double sum =0;
			for (int j = 1; j <=nums[i]; j++) {
				if(j%2==0) {
					sum+=(-1*1.0/j);
				}else {
					sum+=1.0/j;
				}
			}
			list.add(sum);
		}
		DecimalFormat format = new DecimalFormat("0.00");
		for (int i = 0; i < list.size(); i++) {
			System.out.println(format.format(list.get(i)));
		}
		
	}

}

P2012.素数判定

package hdu经典100题;

import java.util.Arrays;
import java.util.Scanner;

public class P2012 {

	public static void main(String[] args) {
		// TODO Auto-generated method stub
		Scanner in = new Scanner(System.in);
            //模拟
		int [] nums = new int[3000];
		nums[2] = 0;
		nums[3] = 0;
		nums[5] = 0;
		for (int i = 2; i < nums.length; i++) {
			int j=2;
			if(nums[i]==0) {
				for (; j*i < nums.length; j++) {
					nums[j*i] = 1;
				}
			}
		}
		while(in.hasNext()) {
			int x = in.nextInt();
			int y = in.nextInt();
			if(x==0 && y==0) {
				break;
			}
			int i;
			for ( i = x; i <=y; i++) {
				if(nums[(i*i+i+41)]!=0) {
					break;
				}
			}
			if(i==y+1) {
				System.out.println("OK");
			}else {
				System.out.println("Sorry");
			}
		}
	}

}

P2013.蟠桃记

package hdu经典100题;

import java.util.Scanner;

public class P2013 {

	public static void main(String[] args) {
		// TODO Auto-generated method stub
		Scanner in = new Scanner(System.in);
		while(in.hasNext()) {
			int n = in.nextInt()-1;
			int amount = 1;
			while(n!=0) {
				amount = 2*(amount+1);
				n--;
			}
			System.out.println(amount);
		}
	}

}

P2014.青年歌手大奖赛_评委会打分

package hdu经典100题;

import java.text.DecimalFormat;
import java.util.ArrayList;
import java.util.Collections;
import java.util.List;
import java.util.Scanner;

public class P2014 {

	public static void main(String[] args) {
		// TODO Auto-generated method stub
		Scanner in = new Scanner(System.in);
		while(in.hasNext()) {
			int n = in.nextInt();
			List<Double> list = new ArrayList<>();
			for (int i = 0; i < n; i++) {
				list.add(in.nextDouble());
			}
			Collections.sort(list);
			list.remove(0);
			list.remove(list.size()-1);
			double sum = 0;
			for (int i = 0; i < list.size(); i++) {
				sum+=list.get(i);
			}
			DecimalFormat format = new DecimalFormat("0.00");
			System.out.println(format.format(sum/list.size()));
		}
	}

}

P2015.偶数求和

package hdu经典100题;

import java.util.ArrayList;
import java.util.List;
import java.util.Scanner;

public class P2015 {

	public static void main(String[] args) {
		// TODO Auto-generated method stub
		Scanner in = new Scanner(System.in);
		int[] nums = new int[100];
		nums[0] = 2;
		for (int i = 1; i < nums.length; i++) {
			nums[i] = nums[i-1]+2;
		}
		while(in.hasNext()) {
			int n = in.nextInt();
			int m = in.nextInt();
			List<Integer> list = new ArrayList<>();
			if(n%m==0) {
				for (int i = 0; i < n; i+=m) {
					int sum = 0;
					for (int j = i; j < i+m;j++) {
						sum+=nums[j];
					}
					list.add(sum/m);
				}
			}else {
				int i = 0;
				for (; i < n-(n%m); i+=m) {
					int sum = 0;
					for (int j = i; j < i+m;j++) {
						sum+=nums[j];
					}
					list.add(sum/m);
				}
				int sum = 0;
				m = n%m;
				for (int j = i; j < n; j++) {
					sum+=nums[j];
				}
				list.add(sum/m);
			}
			
			for (int i = 0; i < list.size()-1; i++) {
				System.out.print(list.get(i)+" ");
			}
			System.out.println(list.get(list.size()-1));
		}
	}

}

P2016.数据的交换输出

package hdu经典100题;

import java.util.Scanner;

public class P2016 {
	public static void main(String[] args) {
		Scanner in = new Scanner(System.in);
		while(in.hasNext()) {
			int n = in.nextInt();
			if(n==0) {
				break;
			}
			int[] nums = new int [n];
			nums[0] = in.nextInt();
			int minIndex = 0;
			int temp;
			for (int i = 1; i < nums.length; i++) {
				nums[i] = in.nextInt();
				if(nums[i]<nums[minIndex]) {
					minIndex = i;
				}
			}
			temp = nums[minIndex];
			nums[minIndex] = nums[0];
			nums[0] = temp;
			for (int i = 0; i < nums.length-1; i++) {
				System.out.print(nums[i]+" ");
			}
			System.out.println(nums[nums.length-1]);
		}
	}
}

P2017.字符串统计

package hdu经典100题;

import java.util.Scanner;

public class P2017 {

	public static void main(String[] args) {
		// TODO Auto-generated method stub
		Scanner in = new Scanner(System.in);
		int n = in.nextInt();
		while(n!=0) {
			String str = in.next().toLowerCase();
			int amount =0;
			for (int i = 0; i < str.length(); i++) {
				if(str.charAt(i)>='0' && str.charAt(i)<='9') {
					amount++;
				}
			}
			System.out.println(amount);
			n--;
		}
	}

}

P2018.母牛的故事

package hdu经典100题;

import java.util.Scanner;

public class P2018 {

	public static void main(String[] args) {
		// TODO Auto-generated method stub
		Scanner in = new Scanner(System.in);
		long[] amount = new long [54];
		amount[0] = 1;
		amount[1] = 2;
		amount[2] = 3;
		amount[3] = 4;
		for (int i = 4; i < amount.length; i++) {
			amount[i] = amount[i-1]+amount[i-3];
		}
		while(in.hasNext()) {
			int n = in.nextInt();
			if(n==0) {
				break;
			}
			System.out.println(amount[n-1]);
		}
	}

}

P2019.数列有序!

package hdu经典100题;

import java.util.ArrayList;
import java.util.List;
import java.util.Scanner;

public class P2019 {

	public static void main(String[] args) {
		// TODO Auto-generated method stub
		Scanner in = new Scanner(System.in);
		while(in.hasNext()) {
			int n = in.nextInt();
			int m = in.nextInt();
			if(n==0 && m==0) {
				break;
			}
			List<Integer> list = new ArrayList<>();
			int insert = n;
			boolean isJ = false;
			for (int i = 0; i < n; i++) {
				list.add(in.nextInt());
				if(list.get(i)>=m && !isJ) {
					insert = i;
					isJ = true;
				}
			}
			list.add(insert, m);
			for (int i = 0; i < list.size()-1; i++) {
				System.out.print(list.get(i)+" ");
			}
			System.out.println(list.get(list.size()-1));
		}
	}

}

P2020.绝对值排序

package hdu经典100题;

import java.util.Scanner;

public class P2020 {

	public static void main(String[] args) {
		// TODO Auto-generated method stub
		Scanner in = new Scanner(System.in);
		while(in.hasNext()) {
			int n = in.nextInt();
			if(n==0) {
				break;
			}
			int[] nums = new int [n];
			for (int i = 0; i < nums.length; i++) {
				nums[i] = in.nextInt();
			}
			int temp;
			for (int i = 0; i < nums.length; i++) {
				for (int j = 0; j < nums.length-1-i; j++) {
					if(Math.abs(nums[j+1])>Math.abs(nums[j])) {
						temp = nums[j+1];
						nums[j+1] = nums[j];
						nums[j] = temp;
					}
				}
			}
			for (int i = 0; i < nums.length-1; i++) {
				System.out.print(nums[i]+" ");
			}
			System.out.println(nums[nums.length-1]);
			
		}
	}

}

未完......(更新中)

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