蓝桥杯练习01

• 母牛的故事

  import java.util.Scanner;

   

  public class Main {

      

      public static void main(String[] args) {

          Scanner in=new Scanner(System.in);

          int n=in.nextInt();

          while (n>0&&n<55) {

              System.out.println(f(n));

              n=in.nextInt();

          }

      }

      private static int f(int n) {

          if (n==0) {

              return 0;

          }

          if (n==1) {

              return 1;

          }

          if (n==2) {

              return 2;

          }

          if (n==3) {

              return 3;

          }

          return f(n-1)+f(n-3);

      }

   

  }

• Hello,World!

  import java.util.Scanner;

   

  public class Main {

      

      public static void main(String[] args) {

          Scanner in=new Scanner(System.in);

          int n;

          while (in.hasNext()) {

              n=in.nextInt();

              System.out.print((char)n);    

          }    

      }

  }

• 用筛法求之N内的素数

  import java.util.Scanner;

   

  public class Main {

      

      public static void main(String[] args) {

          Scanner in=new Scanner(System.in);

          int n=in.nextInt();

          boolean[] notPrime=new boolean[n];

          for (int i = 2; i < n; i++) {

              if (!notPrime[i]) {

                  System.out.println(i);

                  for (int j = 2; j*i < n; j++) {

                      notPrime[i*j]=true;

                  }

              }

          }

      }

  }

• 字符逆序

  import java.util.ArrayList;

  import java.util.Collections;

  import java.util.List;

  import java.util.Scanner;

   

  public class Main {

      

      public static void main(String[] args) {

          Scanner in=new Scanner(System.in);

          String string=in.nextLine();

          List<Character> list=new ArrayList<>();

          for (int i = 0; i < string.length(); i++) {

              list.add(string.charAt(i));

          }

          Collections.reverse(list);

          for (Character c : list) {

              char ch=c;

              System.out.print(ch);

          }

      }

  }

• 字符串的输入输出处理

  import java.util.Scanner;

  public class Main {

      public static void main(String[] args) {

          Scanner in=new Scanner(System.in);

          int n=in.nextInt();

          String s1=in.nextLine();

          while (n>0) {

              s1=in.nextLine();

              System.out.println(s1);

              System.out.println();

              n--;

          }

          String s2;

          while (in.hasNext()) {

              s2=in.next();

              System.out.println(s2);

              System.out.println();

          }

      }

  }

• The 3n+1 Problem    

  import java.util.Scanner;

  public class Main {

      public static void main(String[] args) {

          Scanner in=new Scanner(System.in);

          while (in.hasNext()) {

              int n=in.nextInt();

              int m=in.nextInt();

              System.out.print(n+" "+m+" ");

              int max=0;

              for (int j = Math.min(n, m); j <= Math.max(n, m); j++) {

                  int i=1;

                  int k=j;

                  while (k!=1&&(k>0&&k<1000000)) {

                      if (k%2==0) {

                          k/=2;

                      }else {

                          k=k*3+1;

                      }

                      i++;

                  }

                  max=Math.max(i, max);

              }

              System.out.println(max);

          }

      }

  }

• Minesweeper扫雷

import java.util.Scanner;

public class Main {

    public static void main(String[] args) {

        Scanner in=new Scanner(System.in);

        int n=in.nextInt();

        int m=in.nextInt();

        String s=in.nextLine();//读取回车符，下同

        int c=1;//判断雷的数量

        while (in.hasNext()&&(n!=0||m!=0)) {    

            char[][] a=new char[n+2][m+2];//增加两行两列，便于判断雷的数量，防止数组越界

            for (int i = 0; i < n+2; i++) {

                if (i!=0&&i!=n+1) {

                    s=in.nextLine();

                }

                for (int j = 0; j < m+2; j++) {

                    if (i==0||i==n+1||j==0||j==m+1) {

                        a[i][j]='.';

                    }else {    

                        a[i][j]=s.charAt(j-1);

                    }

                }

            }

            for (int i = 1; i < n+1; i++) {

                for (int j = 1; j < m+1; j++) {

                    if (a[i][j]=='*') {

                        continue;

                    }else {

                        int num=0;

                        for (int k = i-1; k <= i+1; k++) {

                            for (int l = j-1; l <= j+1; l++) {

                                if (k==i&&l==j) {

                                    continue;

                                }else if(a[k][l]=='*'){

                                    num++;

                                }

                            }

                        }

                        a[i][j]=(char)(num+48);

                    }

                }

            }

            System.out.println("Field #"+c+":");

            for (int i = 1; i < n+1; i++) {

                for (int j = 1; j < m+1; j++) {

                    System.out.print(a[i][j]);

                }

                System.out.println();

            }

            System.out.println();

            n=in.nextInt();

            m=in.nextInt();

            s=in.nextLine();

            c++;

        }

        

    }

}