java水题集

POJ - 1220　进制转换　

 import java.io.*;
 import java.util.*;
 import java.math.*;

 public class Main {
     public static int GetNum(char c)
     {
         if (Character.isDigit(c))return c-'0';
         if (Character.isUpperCase(c))return c-'A'+10;
         if (Character.isLowerCase(c))return c-'a'+36;
         return '0';
     }
     public static char GetChar(int x)
     {
         if (x<10)return (char)(x+'0');
         else if (x<=35) return (char)(x+'A'-10);
         else return (char)(x+'a'-36);
     }
     public static void main(String[] args)
     {
         Scanner cin= new Scanner(new BufferedInputStream(System.in));
         int T=cin.nextInt();
         while(T--!=0)
         {
             BigInteger base1=cin.nextBigInteger();
             BigInteger base2=cin.nextBigInteger();
             BigInteger n=BigInteger.ZERO;
             String s=cin.next();
             for(int i=0;i<s.length();i++)
             {
                 char c=s.charAt(i);
                 n=n.multiply(base1).add(BigInteger.valueOf(GetNum(c)));
             }
             String ans=new String();
             while(!n.equals(BigInteger.ZERO))
             {
                 ans=GetChar(n.mod(base2).intValue())+ans;
                 n=n.divide(base2);
             }
             if(ans.length()==0) ans+='0';
             System.out.println(base1+" "+s);
             System.out.println(base2+" "+ans);
             if (T>0)System.out.println();
         }

     }

 }

POJ - 1131进制转换

 import java.io.*;
 import java.math.*;
 import java.util.*;
 public class Main {

     public static void main(String[] args)
     {
         Scanner cin=new Scanner(new BufferedInputStream(System.in));
         BigDecimal b= new BigDecimal("8"),k,ans;
         String s;
         while(cin.hasNext())
         {
             ans=new BigDecimal(0);
             k=new BigDecimal(1);
             s=cin.nextLine();
             for(int i=2;i<s.length();i++)
             {
                 k=k.divide(b);
                 ans=ans.add( BigDecimal.valueOf(s.charAt(i)-'0').multiply(k));
             }
             System.out.println(s+" [8] = "+ans.toString()+" [10]");
             //System.out.println(s+" [8] = "+ans.toString()+" [10]");
         }
     }

 }

POJ - 1205 矩阵加速递推

 import java.io.*;
 import java.math.*;
 import java.util.*;
 public class Main {

     public static void main(String[] args)
     {
         Scanner cin=new Scanner(new BufferedInputStream(System.in));
         BigInteger f[]=new BigInteger[1005],Three=BigInteger.valueOf(3);
         BigInteger tp[][]=new BigInteger[3][3],a[][]=new BigInteger[3][3];
         a[1][1]=Three; a[1][2]=BigInteger.valueOf(-1);
         a[2][1]=BigInteger.ONE; a[2][2]=BigInteger.ZERO;
         f[0]=BigInteger.ZERO;
         f[1]=BigInteger.ONE;
         for(int i=2;i<=1000;i++)
             f[i]=f[i-1].multiply(Three).subtract(f[i-2]);
         while(cin.hasNext())
         {
             int n=cin.nextInt();
             tp=MatrixPower(a,2,n-1);
             System.out.println(tp[1][1].toString());
         }
     }
     public static BigInteger[][] MatrixMultiply(BigInteger a[][],BigInteger b[][],int n,int p,int m)
     {
         BigInteger c[][]=new BigInteger[n+1][m+1];
         for(int i=1;i<=n;i++)
         for(int j=1;j<=m;j++)
             c[i][j]=BigInteger.ZERO;
         for(int i=1;i<=n;i++)
         for(int j=1;j<=m;j++)
         for(int k=1;k<=p;k++)
             c[i][j]=c[i][j].add(a[i][k].multiply(b[k][j]));
         return c;
     }
     public static BigInteger[][] MatrixPower(BigInteger a[][],int n,int p)
     {
         BigInteger ans[][]=new BigInteger[n+1][n+1];
         for(int i=1;i<=n;i++)
         for(int j=1;j<=n;j++)
             if (i==j)ans[i][j]=BigInteger.ONE;
             else ans[i][j]=BigInteger.ZERO;
         while(p>0)
         {
             if ((p&1)==1)ans=MatrixMultiply(ans,a,n,n,n);
             p=p/2;
             a=MatrixMultiply(a,a,n,n,n);
         }
         return ans;
     }
 }