C++博客-^^想你-文章分类-JAVA

Java 实现 cmd 功能

Huicpc217 — Sat, 02 Jul 2011 04:31:00 GMT

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;

public class RuntimeComplie {
    public static void main(String[] args) throws IOException, InterruptedException {
        Process p = Runtime.getRuntime().exec("cmd /c javac TestB.java & java TestB");
        InputStream is = p.getInputStream();
        BufferedReader br = new BufferedReader(new InputStreamReader(is));
        String line = null;
        while((line=br.readLine()) !=null) {
            System.out.println(line);
        }
        br.close();
    }
}

Huicpc217 2011-07-02 12:31 发表评论

22

Huicpc217 — Wed, 21 Oct 2009 06:14:00 GMT

import java.io.FileNotFoundException;

import java.io.FileReader;

import java.util.*;

public class Main {

public static void main(String[] args) throws FileNotFoundException {

Scanner cin = new Scanner ( new FileReader("in.txt") );

}

Huicpc217 2009-10-21 14:14 发表评论

Java 文档

Huicpc217 — Tue, 29 Sep 2009 11:35:00 GMT

接口的作用，一言以蔽之，就是标志类的类别（type of class）。
继承的本意在于抽象，而非代码重用
什么时候应该使用继承？只在抽象类中使用，其他情况下尽量不使用。抽象类也是不能实例化的，它仅仅提供一个模版而已。

Huicpc217 2009-09-29 19:35 发表评论

java HashMap

Huicpc217 — Fri, 18 Sep 2009 11:59:00 GMT

//import java.io.*;
import java.util.*;

class Point{
    int x;
    int y;

    public Point( int x, int y ){
        this.x = x;
        this.y = y;
    }

    public void print(){
        System.out.println( "" + x + " " + y );
    }
}

public class Main{
    public static void main( String [] args )throws Exception{

        HashMap<Point, Integer> mymap = new HashMap<Point, Integer>();

        mymap.clear();
        Point [] test = new Point[10];

        for( int i = 0; i < test.length; i++ ){
            test[i] = new Point( 0, i * i - 10 * i + 25 );
            mymap.put( test[i] , i );
        }

        for( int i = 0; i < test.length; i++ ){
            System.out.println( mymap.get( test[i] ) );
        }
    }
}

Huicpc217 2009-09-18 19:59 发表评论

Java sort

Huicpc217 — Sat, 22 Aug 2009 13:55:00 GMT

import java.util.*;

class Point implements Comparable{
    int x;
    int y;

    public Point(){
        x = 0;
        y = 0;
    }

    public void setarg( int x, int y ){
        this.x = x;
        this.y = y;
    }

    public int getx(){
        return x;
    }

    public int gety(){
        return y;
    }

    public int compareTo( Object tmp ){
        Point res = ( Point )tmp;

        if( x < res.x || x == res.x && y < res.y ){
            return -1;
        }
        else{
            return 1;
        }
    }

}

public class Main{
    /*
    boolean comparetor( Point a, Point b ){
        if( a.x < b.x | a.x == b.x && a.y < b.y ){
            return true;
        }
        else{
            return false;
        }
    }
    */
    public static void main( String args[] ) throws Exception{

        Point [] res = new Point[10];

        for( int i = 0; i < res.length; i++ ){
            res[i] = new Point();
        }

        for(int i = 0; i < res.length; i++){
            res[i].setarg( i * i - 10 * i + 25, 0 );
        }

        Arrays.sort( res );

        for( int i = 0; i < res.length; i++ ){
            System.out.println( res[i].getx() + res[i].gety() );
        }

    }
}

Huicpc217 2009-08-22 21:55 发表评论

Java 优先队列

Huicpc217 — Sat, 22 Aug 2009 13:53:00 GMT

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

class Point{
    int x;
    int y;

    public Point( int x, int y ){
        this.x = x;
        this.y = y;
    }
    public void print(){
        System.out.println( "" + x + " " + y );
    }
}

public class Main{
    public static void main( String [] args )throws Exception{

        Scanner cin = new Scanner( System.in );

        int n = cin.nextInt();

        PriorityQueue queue = new PriorityQueue<Point>( 1, new Comparator<Point>(){
            public int compare( Point a, Point b ){
                if( a.x < b.x || a.x == b.x && a.y < b.y ){
                    return -1;
                }
                else if( a.x == b.x && a.y == b.y ){
                    return 0;
                }
                else{
                    return 1;
                }
            }
        });

        for( int i = 0; i < n; i++ ){
            int x = cin.nextInt();
            int y = cin.nextInt();

            Point p = new Point( x, y );

            queue.add( p );
        }

        while( queue.size() > 0 ){
            Point p = ( Point )queue.poll();

            p.print();
        }
    }
}

Huicpc217 2009-08-22 21:53 发表评论

Java 注意

Huicpc217 — Sat, 22 Aug 2009 11:46:00 GMT

类中的对象.（Java 区分简单类型和对象）
获得类的对象的过程包含两个步骤，首先，必须声明该类型的一个变量，这种声明只是一种简单的声明，对计算机而言，并没有分配给实际的物理内存。然后需要创建一个对象的实际物理备份，并把对于该对象的引用赋给该变量。

当传给方法的是一个对象时，是传引用的如果是传递一个简单类型，就是按值传递。

new 运算符可以为对象动态分配内存空间，并返回对它的一个引用，这个引用就是new分配给对象的内存地址，然后这个内存地址被存储在该变量中。

point p; p = z;(这里p是z的引用)
point p = new point(); p = z; (这里p只是z的值)

如果使用this关键字，就可以实现变量的重名。
如：point( double x,double y){
       this.x = x; this.y = y;
    }

point p = new point( z );//重载构造函数

java 的数组可以精确地知道其大小，对其进行范围内的操作。

static 函数只操作 static 型变量。static是完全独立于该类的任何对象。
static{ }函数，类装载时调用一次。

java 中常量是 final   。如： final int quit = 5;

嵌套类和内部类...以后再学吧...

Huicpc217 2009-08-22 19:46 发表评论

高斯消元 Java 高精度版 HDU 2449 Gauss Elimination

Huicpc217 — Fri, 21 Aug 2009 18:36:00 GMT

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

class fraction{
    BigInteger a, b;
    public fraction(){
        a = new BigInteger("0");
        b = new BigInteger("1");
    }

    fraction( BigInteger a0, BigInteger b0){
        this.a = a0; this.b = b0;
    }
    void reduction(){
        BigInteger tmp = a.gcd( b );
        a = a.divide( tmp );
        b = b.divide( tmp );
        if( b.compareTo( BigInteger.ZERO ) == - 1 )
        {
            b = b.multiply( BigInteger.valueOf( -1 ));
            a = a.multiply( BigInteger.valueOf( -1 ));
        }
    }
    fraction add( fraction t ){
        fraction tmp = new fraction( a.multiply( t.b ).add( b.multiply( t.a )) , b.multiply(t.b) );
        tmp.reduction();
        return tmp;
    }
    fraction sub( fraction t ){
        fraction tmp = new fraction( a.multiply( t.b ).subtract( b.multiply( t.a )) , b.multiply(t.b) );
        tmp.reduction();
        return tmp;
    }
    fraction mult( fraction t){
        fraction tmp = new fraction( a.multiply( t.a ), b.multiply( t.b ));
        tmp.reduction();
        return tmp;
    }
    fraction div( fraction t){
        fraction tmp = new fraction( a.multiply( t.b ), b.multiply( t.a ));
        tmp.reduction();
        return tmp;
    }
    public void abs(){
        if( this.a.compareTo( BigInteger.ZERO ) == - 1 ){
            this.a = this.a.multiply( BigInteger.valueOf( -1 ));
        }
    }
    void out(){
        this.reduction();
        if( b.compareTo( BigInteger.ONE ) == 0 )
            System.out.println(a);
        else
            System.out.println(a+"/"+b);
    }

    boolean biger( fraction p ){
        fraction tmp = new fraction ( a, b );
        fraction t = new fraction(p.a,p.b);
        //t = p;
        tmp.reduction();
        if( tmp.a.compareTo( BigInteger.ZERO ) == - 1 ){
            tmp.a = tmp.a.multiply( BigInteger.valueOf( -1 ));
        }
        if( t.a.compareTo( BigInteger.ZERO ) == - 1 ){
            t.a = t.a.multiply( BigInteger.valueOf( -1 ));
        }
        tmp = tmp.sub( t );
        return tmp.a.compareTo( BigInteger.ZERO ) > -1;
    }

}

public class Main{

    public static void lup_solve( fraction x[],fraction y[], fraction L[][], fraction U[][],int pi[],fraction b[],int n)
    {
        int i, j;
        fraction z = new fraction( BigInteger.ZERO , BigInteger.ONE);
        fraction sum = z;//double sum;
        for ( i = 0 ; i < n ; i ++ ){
            sum = z; //sum = 0;
            for ( j = 0 ; j < i ; j ++ ){
                sum = sum.add( L[i][j].mult( y[j] ));//sum += L[i][j] * y[ j ];
            }
            y[i] = b[ pi[i] ].sub( sum );//y[i] = b[ pi[i] ] - sum;
        }
        for ( i = n - 1 ; i >= 0 ; i -- ){
            sum = z ; //sum = 0;
            for ( j = i + 1 ; j < n ; j ++ ){
                sum = sum.add( U[i][j].mult( x[j] ));//sum += U[i][j] * x[ j ];
            }
            x[i] = (y[i].sub( sum )).div( U[i][i] );//x[i] = (y[i] - sum)/U[i][i];
        }
    }

    public static int lup_decomposition( fraction a[][] , int n , int pi[] )
    {
        int i, j, k, k1 = 0 ;
        fraction p = new fraction(BigInteger.valueOf(0), BigInteger.ONE ), z = new fraction( BigInteger.valueOf(0), BigInteger.ONE );
        for ( i = 0 ; i < n ; i ++ )
            pi[i] = i;// 置换

        for ( k = 0 ; k < n ; k ++ ){
            p = z;
            for ( i = k ; i < n ; i ++ )
            {
                if(  a[i][k].biger( p ) )
                {
                    p = new fraction( a[i][k].a,a[i][k].b) ;
                    k1 = i;
                }
            }
            if( p.a.compareTo( BigInteger.ZERO ) == 0 ){
                return 0 ;// error
            }
            fraction tmp;

            int t = pi[ k ]; pi[ k ] = pi[ k1 ]; pi[k1] = t;
            for ( i = 0 ; i < n ; i ++ ){
                tmp = a[ k ][i];  a[ k ][i] = a[ k1 ][i];  a[k1][i] = tmp;
            }//swap( a[k][i], a[k1][i] );
            for ( i = k + 1 ; i < n ; i ++ )
            {
                a[i][k] = a[i][k].div( a[k][k] );
                for ( j = k + 1 ; j < n ; j ++ )
                    a[i][j] = a[i][j].sub( a[i][k].mult(a[k][j]));// - a[i][k] * a[k][j] ;
            }
        }
        return 1;
    }

    public static void check(fraction a[][], fraction x[], int n){
        int i, j;
        fraction sum, z = new fraction( BigInteger.ZERO , BigInteger.ONE);
        for ( i = 0 ;  i < n ; i++ ){
            sum = z;
            for ( j = 0 ;j < n ; j ++ )
            {
                sum = sum.add( a[i][j].mult( x[j] ));
            }
            sum.out();
        }
    }

    public static void main(String[] agrs){
        Scanner cin = new Scanner( System.in );
        int i, j;
        int n;
        while( cin.hasNextInt() )
        {
            //任何函数都要和一个class相连
            n = cin.nextInt();
            int pi[] = new int[n];
            fraction a[][] = new fraction[n][n];
            fraction aa[][] = new fraction[n][n];
            fraction B[] = new fraction[n];
            fraction x[] = new fraction[n];
            fraction y[] = new fraction[n];

            for ( i = 0 ; i < n ; i ++ )
            {
                for ( j = 0 ;j < n ; j ++ ){
                    a[i][j] = new fraction( BigInteger.valueOf(0),BigInteger.valueOf(1));
                    a[i][j].a = cin.nextBigInteger();
                    aa[i][j] = new fraction( BigInteger.valueOf(0),BigInteger.valueOf(1));
                    aa[i][j] = a[i][j];
                }
                B[i] = new fraction( BigInteger.valueOf(0),BigInteger.valueOf(1));
                B[i].a = cin.nextBigInteger();
                x[i] = new fraction( BigInteger.valueOf(0),BigInteger.valueOf(1));
                y[i] = new fraction( BigInteger.valueOf(0),BigInteger.valueOf(1));
            }
            if( 1 == lup_decomposition( a, n, pi) )
            {
                lup_solve( x, y, a, a, pi, B, n);
                for ( i = 0 ;i < n; i ++)
                    x[i].out();
                //check( aa, x, n);
            }
            else
            {
                System.out.println("No solution.");
            }
            System.out.println();
        }
    }
}

Huicpc217 2009-08-22 02:36 发表评论

Toj 3218. Pendant Java

Huicpc217 — Tue, 18 Aug 2009 11:34:00 GMT

import java.util.*;

class Matrix{
    static final int M = 1234567891;
    public int a[][] ;
    public int n ;
    Matrix( int _n , int val){
        int i , j ;
        n = _n ;
        a = new int[n][n];
        for ( i = 0 ; i < n ; i ++ )
        {
            for ( j = 0 ;j < n ;j ++ )
            if ( i == j )
                a[i][j] = val;
            else
                a[i][j]  = 0 ;
        }
    }
    Matrix mult ( Matrix b ){
        Matrix ret = new Matrix(n,0);
        int i , j , k ;
        for ( i = 0 ; i < n ; i ++ )
        {
            for ( j = 0 ; j < n ; j ++ )
            {
                for ( k = 0 ; k < n ; k ++ )
                    ret.a[i][j] = (int)(((long)a[i][k] * b.a[k][j] + ret.a[i][j]) % M);
                                    //(int)必须要使用
            }
        }
        return ret;
    }

    Matrix pow ( int p ){
        Matrix ret = new Matrix ( n , 1 );
        Matrix t = this ;
        while ( p > 0 )
        {
            if ( (p & 1) != 0 ) ret = ret .mult(t);
            p >>= 1  ;
            //ret.show();
            t = t.mult(t);
        }

        return ret;
    }
    void show()
    {
        int i , j ;
        for ( i = 0 ; i <  n ; i ++)
        {
            for ( j = 0 ; j < n ; j ++)
            {
                System.out.print(a[i][j]+ " ");
            }
            System.out.println();

        }
        System.out.println();
    }
}

public class Main{
    public static void main(String [] args)throws Exception
    {
        Scanner cin = new Scanner ((System.in));
        int test = cin.nextInt();
        int n , K  ;
        while ( test > 0 )
        {
            test -- ;
            n = cin.nextInt();
            K = cin.nextInt();
            Matrix g = new Matrix ( 2 * ( K + 1 ) , 1 );
            for ( int i = 0 ; i <= K ; i ++ )
            {
                g.a[i][i] = i ;
                if ( i > 0 )
                    g.a[i][i-1] = K - i + 1;
            }
            for ( int i = 0 ; i <= K ; i ++ ){
                g.a[K + 1 + i ] [ i ] = 1;
            }
            Matrix gg = g.pow(n);
            //g.show();
            //gg.show();
            System.out.println((long)gg.a[2*K+1][1]*K%1234567891);
        }
    }
}

Huicpc217 2009-08-18 19:34 发表评论

Toj 3217. Name PK Java

Huicpc217 — Tue, 18 Aug 2009 11:33:00 GMT

import java.util.*;
public class Main{
    public static void main(String [] args)
    {
        Scanner cin = new Scanner( System.in);
        int test;
        test = cin.nextInt();
        while ( test > 0)
        {
            test -- ;
            String s = cin.next();
            String t = cin.next();
            char a[] = s.toCharArray();
            int hp1 = 0 , hp2 = 0 , str1 = 1 , str2 = 1 , spd1 = 0 , spd2 = 0 ;
            for ( int i = 0 ; i < s.length(); i ++ )
            {
                hp1 = ( hp1 + (83 - (int)s.charAt(i))*(83 - (int)s.charAt(i))) % 97 ;
                str1 = ( str1 * (int)s.charAt(i) ) % 79 ;
                for ( int j = i + 1 ; j < s.length() ; j ++ )
                {
                    spd1 = ( spd1 + (int)a[j] * (int)a[i])%11 ;
                }
            }
            str1 += 22 ;
            hp1 = 300 - hp1 ;
            for ( int i = 0 ; i < t.length(); i ++ )
            {
                hp2 = ( hp2 + (83 - (int)t.charAt(i))*(83 - (int)t.charAt(i))) % 97 ;
                str2 = ( str2 * (int ) t.charAt(i))%79;
                for ( int j = i + 1 ;j < t.length() ; j ++ )
                {
                    spd2 = ( spd2 + (int ) t.charAt(j) * (int ) t.charAt(i))%11 ;
                }
            }
            str2 += 22;
            hp2 = 300 - hp2 ;
            int t1 = hp2 / str1 ;
            if ( hp2 % str1 != 0 )
                t1 ++ ;
            int t2 = hp1 / str2 ;
            if ( hp1 % str2 != 0 )
                t2 ++ ;
            t1 *= ( 20 - spd1 );
            t2 *= ( 20 - spd2 );
            if ( t1 == t2 )
                System.out.println("tie");
            else
                System.out.println((t1<t2?"win":"lose"));
        }
    }

}

Huicpc217 2009-08-18 19:33 发表评论

Toj 3222 Toxophily Java

Huicpc217 — Tue, 18 Aug 2009 11:31:00 GMT

import java.util.*;
import java.text.*;
public class Main{

    public static void main(String [] args)
    {
        final double eps = 1e-10;
        final double g = 9.8;
        Scanner cin = new Scanner ( System.in );
        int test = cin.nextInt();
        double x , y , v , delt , t ;
        DecimalFormat ctrl = new DecimalFormat ( "0.000000");
        while ( test > 0 )
        {
            test -- ;
            x = cin.nextDouble();
            y = cin.nextDouble();
            v = cin.nextDouble();
            t = g * x *x / ( v * v );
            delt = x * x - t * ( t + 2 * y );
            if ( delt > - eps )
            {
                double rel = (Math.atan((x-Math.sqrt( delt ))/t));
                System.out.println(ctrl.format(rel));
            }
            else
            {
                System.out.println("-1");
            }
        }
    }
}

Huicpc217 2009-08-18 19:31 发表评论

Toj 3213 Cup Java

Huicpc217 — Tue, 18 Aug 2009 11:30:00 GMT

import java.util.*;
import java.text.*;
public class Main {
    public static void main(String [] args)
    {
        final double eps = 1e-8;
        final double pi = Math.acos( - 1.0 );
        DecimalFormat ctrl = new DecimalFormat( "0.000000" );
        Scanner cin = new Scanner ( System.in);
        double r,R,tmp,h,H,V,h1,b,e,mid;
        int test = cin.nextInt();
        while ( test -- > 0 )
        {
            r = cin.nextDouble();
            R = cin.nextDouble();
            H = cin.nextDouble();
            V = cin.nextDouble();
            if ( r == R)
            {
                h = V / (pi*r*r);
                h = h < H ? h : H;
                System.out.println(ctrl.format(h));
                continue;
            }

            h1 =  r * H / ( R - r );
            b = 0 ; e = H ;
            while ( b < e - eps)
            {
                mid = ( b + e ) * 0.5;
                h = mid ;
                tmp = ( pi*(h+h1)*(h+h1)*(h+h1)*r*r/ (h1 * h1 *3.0) - pi * (h1)*r * r  / 3.0  );
                if ( tmp < V )
                {
                    b = mid;
                }
                else
                {
                    e = mid;
                }
            }
            System.out.println(ctrl.format(b));
        }
    }

}