算法之路——POJ刷题（Java，持续更新中）

先拿一些水题来练手了

1.POJ1000

简单的计算a+b，就不多说了

import java.util.Scanner;

/**
 * Created by mxcsky on 2015/1/25.
 */
public class POJ1000 {
    public static void main(String[] args){
        Scanner in = new Scanner(System.in);
        int a = in.nextInt();
        int b = in.nextInt();
        System.out.println(a + b);
    }
}

2.POJ1003

给定长度c，求满足1/2 + 1/3 + 1/4 + ... + 1/(n + 1) >= c所需要的最小正整数n，这里需要注意的是，当c <= 1/2时，都只需1 card(s)，另外判断浮点数是否为0.00时，我使用的是

if (m < 0.00001)

若使用

if (m == 0.00)

也可以通过POJ系统，不知道这里是否正确，希望读者能够指正

import java.util.Scanner;

/**
 * Created by mxcsky on 2015/1/25.
 */
public class POJ1003 {
    public static void main(String[] args){
        Scanner in = new Scanner(System.in);
        while(true) {
            double m = in.nextDouble();
            double sum = 0.0;
            int i = 1;
            if (m < 0.00001) {
                System.exit(0);
            }
            if (m <= 0.5) {
                System.out.println("1 card(s)");

            } else {
                while (sum < m) {
                    i++;
                    sum = sum + 1.0 / i;

                }
                System.out.println((i - 1) + " card(s)");
            }
        }
    }
}

3.POJ1004

求12个月的平均余额，输出以$开头，精确到美分（即小数点第二位）

import java.util.Scanner;

/**
 * Created by mxcsky on 2015/1/25.
 */
public class POJ1004 {
    public static void main(String[] args){
        Scanner in = new Scanner(System.in);
        double sum = 0.0;
        for (int i = 0; i < 12; i++){
            sum = sum + in.nextDouble();
        }
        System.out.printf("$%.2f", sum/12);
    }
}

 4.POJ1207

根据给定的算法得出循环数，注意输入有可能不是从小到大，所以需要排序，但是输出时要按照原顺序输出，例如输入200 100，输出200 100 125

import java.util.Scanner;

/**
 * Created by mxcsky on 2015/1/25.
 */
public class POJ1207 {
    public static void main(String[] args){
        Scanner in = new Scanner(System.in);
        String str = new String();
        while (in.hasNext()){
            str = in.nextLine();
            String[] array = str.split(" ");
            int i = Integer.parseInt(array[0]);
            int j = Integer.parseInt(array[1]);
            int t = 0;
            int signal = 0;
            int num = 0;
            int max = 0;
            int n = 0;
            if (i > j){
                t = i;
                i = j;
                j = t;
                signal = 1;
            }
            else {
                signal = 0;
            }
            for(int temp = i; temp <= j; temp++){
                n = temp;
                while (true){
                    if (n == 1){
                        num++;
                        break;
                    }
                    else {
                        if (n % 2 == 1){
                            n = 3 * n + 1;
                            num++;
                        }
                        else {
                            n = n / 2;
                            num++;
                        }
                    }
                }
                if (max < num){
                    max = num;
                }
                num = 0;
            }
            if (signal == 0){
                System.out.println(i+" "+j+" "+max);
            }
            else {
                System.out.println(j+" "+i+" "+max);
            }

        }
    }
}