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;
    }
}