Java Java Java

学下java 的大数该怎么用><

求卡特兰数

诶...不记得卡特兰数的我眼泪掉下来

第一次用 java 大数有点激动...><

 import java.io.*;

 import java.util.*;

 import java.math.BigInteger;

 public class test{

     public static void main(String args[]){

         BigInteger[] a = new BigInteger[];

         a[] = BigInteger.ZERO;

         a[] = BigInteger.ONE;

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

             BigInteger l = BigInteger.valueOf(*i-);

             BigInteger r = BigInteger.valueOf(i+);

             a[i] = a[i-].multiply(l);

             a[i] = a[i].divide(r);

         }

         Scanner in = new Scanner(System.in);

         int n;

         while(in.hasNext()){

             n = in.nextInt();

             System.out.println(a[n]);

         }

     }

 }

hdu 1063 Exponentiation

求小数 a 的 b 次方

stripTrailingZeros：去掉末尾0

toPlainStrin：将科学计数法表示正常写法

startWith：去掉首位0

subtring(x) ：截取从第 x 位往后的字符串

 import java.io.*;

 import java.util.*;

 import java.math.BigDecimal;

 import java.math.BigInteger;

 public class test{

     public static void main(String args[]){

         Scanner in = new Scanner(System.in);

         while(in.hasNext()){

             BigDecimal a = in.nextBigDecimal();

             int b = in.nextInt();

             String ans = a.pow(b).stripTrailingZeros().toPlainString();

             if(ans.startsWith("")){

                 ans = ans.substring();

             }

             System.out.println(ans);

         }

     }

 }

不过看C++的都是 0 ms 过，java要跑 500多ms

hdu 1047 Integer Inquiry

大数相加

 import java.io.*;

 import java.util.*;

 import java.math.BigDecimal;

 import java.math.BigInteger;

 public class Main{

     public static void main(String args[]){

         Scanner in = new Scanner(System.in);

         int n = in.nextInt();

         while(n-- > ){

             BigInteger ans = BigInteger.ZERO;

             while(in.hasNext()){

                 BigInteger tmp = BigInteger.ZERO;

                 tmp = in.nextBigInteger();

                 BigInteger zero = BigInteger.valueOf();

                 if(!tmp.equals(zero)){

                     ans = ans.add(tmp);

                 }

                 else{

                     System.out.println(ans);

                     if(n != ) System.out.println("");

                     break;

                 }

             }

        }

    }

 }

hdu 1316 How Many Fibs?

统计大数区间里面的斐波那契数的个数

用到一个 compareto

 import java.io.*;

 import java.util.*;

 import java.math.BigDecimal;

 import java.math.BigInteger;

 public class Main{

     public static void main(String args[]){

         Scanner in = new Scanner(System.in);

         BigInteger f[] = new BigInteger[];

         BigInteger zero = BigInteger.ZERO;

         f[] = new BigInteger("");

         f[] = new BigInteger("");

         for(int i = ;i <= ;i++) f[i] = f[i-].add(f[i-]);

         while(in.hasNext()){

             BigInteger l = in.nextBigInteger();

             BigInteger r = in.nextBigInteger();

             if(l.compareTo(zero) ==  && r.compareTo(zero) == ) break;

             int ans = ;

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

                 if(l.compareTo(f[i]) <=  && r.compareTo(f[i]) >= ) ans++;

             }

             System.out.println(ans);

         }

    }

 }

hdu 1753 大明A+B

大实数相加

 import java.io.*;

 import java.util.*;

 import java.math.BigDecimal;

 public class Main {

     public static void main(String[] args)

     {

         Scanner in=new Scanner(System.in);

         while (in.hasNext())

         {

             BigDecimal a=in.nextBigDecimal();

             BigDecimal b=in.nextBigDecimal();

             a=a.add(b);

             String s=a.stripTrailingZeros().toPlainString();

          //   if (s.startsWith("0."))

            //     s=s.substring(1);

             System.out.println(s);

         }

     }

 }

hdu 1261 字串数

大数阶乘，除法

 import java.io.*;

 import java.util.*;

 import java.math.BigDecimal;

 import java.math.BigInteger;

 public class Main{

     public static void main(String args[]){

         Scanner in = new Scanner(System.in);

         int[] a = new int[];

         BigInteger[] f = new BigInteger[];

         f[] = BigInteger.ONE;

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

             BigInteger tmp = BigInteger.valueOf(i);

             f[i] = f[i-].multiply(tmp);

         }

         int n;

         while(in.hasNext()){

             n = in.nextInt();

             if(n == ) break;

             int x;

             BigInteger fz ,fm;

             fm = BigInteger.ONE;

             int fzz = ,fmm = ;

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

                 a[i] = in.nextInt();

                 fzz = fzz + a[i];

                 fm = fm.multiply(f[a[i]]);

             }

             fz = f[fzz];

             //System.out.println(fz);

             //System.out.println(fm);

             BigInteger ans = fz.divide(fm);

             System.out.println(ans);

         }

    }

 }

java 板

 //卡特兰数

 import java.io.*;

 import java.util.*;

 import java.math.BigInteger;

 public class test{

     public static void main(String args[]){

         BigInteger[] a = new BigInteger[];

         a[] = BigInteger.ZERO;

         a[] = BigInteger.ONE;

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

             BigInteger l = BigInteger.valueOf(*i-);

             BigInteger r = BigInteger.valueOf(i+);

             a[i] = a[i-].multiply(l);

             a[i] = a[i].divide(r);

         }

         Scanner in = new Scanner(System.in);

         int n;

         while(in.hasNext()){

             n = in.nextInt();

             System.out.println(a[n]);

         }

     }

 }

 /*求小数 a 的 b 次方

 stripTrailingZeros：去掉末尾0

 toPlainStrin：将科学计数法表示正常写法

 startWith：去掉首位0

 subtring(x) ：截取从 第 x 位往后的字符串*/

 import java.io.*;

 import java.util.*;

 import java.math.BigDecimal;

 import java.math.BigInteger;

 public class test{

     public static void main(String args[]){

         Scanner in = new Scanner(System.in);

         while(in.hasNext()){

             BigDecimal a = in.nextBigDecimal();

             int b = in.nextInt();

             String ans = a.pow(b).stripTrailingZeros().toPlainString();

             if(ans.startsWith("")){

                 ans = ans.substring();

             }

             System.out.println(ans);

         }

     }

 }

 //大数相加

 import java.io.*;

 import java.util.*;

 import java.math.BigDecimal;

 import java.math.BigInteger;

 public class Main{

     public static void main(String args[]){

         Scanner in = new Scanner(System.in);

         int n = in.nextInt();

         while(n-- > ){

             BigInteger ans = BigInteger.ZERO;

             while(in.hasNext()){

                 BigInteger tmp = BigInteger.ZERO;

                 tmp = in.nextBigInteger();

                 BigInteger zero = BigInteger.valueOf();

                 if(!tmp.equals(zero)){

                     ans = ans.add(tmp);

                 }

                 else{

                     System.out.println(ans);

                     if(n != ) System.out.println("");

                     break;

                 }

             }

        }

    }

 }

 //大实数相加

 import java.io.*;

 import java.util.*;

 import java.math.BigDecimal;

 public class Main {

     public static void main(String[] args)

     {

         Scanner in=new Scanner(System.in);

         while (in.hasNext())

         {

             BigDecimal a=in.nextBigDecimal();

             BigDecimal b=in.nextBigDecimal();

             a=a.add(b);

             String s=a.stripTrailingZeros().toPlainString();

          //   if (s.startsWith("0."))

            //     s=s.substring(1);

             System.out.println(s);

         }

     }

 }

 //大数阶乘，除法

 import java.io.*;

 import java.util.*;

 import java.math.BigDecimal;

 import java.math.BigInteger;

 public class Main{

     public static void main(String args[]){

         Scanner in = new Scanner(System.in);

         int[] a = new int[];

         BigInteger[] f = new BigInteger[];

         f[] = BigInteger.ONE;

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

             BigInteger tmp = BigInteger.valueOf(i);

             f[i] = f[i-].multiply(tmp);

         }

         int n;

         while(in.hasNext()){

             n = in.nextInt();

             if(n == ) break;

             int x;

             BigInteger fz ,fm;

             fm = BigInteger.ONE;

             int fzz = ,fmm = ;

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

                 a[i] = in.nextInt();

                 fzz = fzz + a[i];

                 fm = fm.multiply(f[a[i]]);

             }

             fz = f[fzz];

             //System.out.println(fz);

             //System.out.println(fm);

             BigInteger ans = fz.divide(fm);

             System.out.println(ans);

         }

    }

 }

 /*主类名字必须是Main

 读一个整数：    int n = cin.nextInt();

 读一个字符串：String s = cin.next();

 读一个浮点数：double t = cin.nextDouble();

 读一整行：      String s = cin.nextLine();

 判断是否有下一个输入可以用 cin.hasNext() 或 cin.hasNextInt() 或 cin.hasNextDouble() 等

 输出浮点数保留位数

 DecimalFormat f = new DecimalFormat("#.00#");

 DecimalFormat g = new DecimalFormat("0.000");

 double a = 123.45678, b = 0.12;

 System.out.println(f.format(a));

 System.out.println(f.format(b));

 System.out.println(g.format(b)); 

 大数的运算

 BigInteger add(BigInteger other)

 BigInteger subtract(BigInteger other)

 BigInteger multiply(BigInteger other)

 BigInteger divide(BigInteger other)

 BigInteger mod(BigInteger other)

 int compareTo(BigInteger other)

 static BigInteger valueOf(long x) 

 输出直接用  System.out.println(a)*/

 StringBuffer

 import java.io.*;

 import java.util.*;

 import java.text.*;

 import java.math.BigDecimal;

 import java.math.BigInteger;

 public class test{

     public static void main(String args[]){

         //赋值

         StringBuffer a = new StringBuffer();//初始化

         StringBuffer b = new StringBuffer("abc");

         String c = "abc";

         StringBuffer d = new StringBuffer(c);

         //在末尾加

         StringBuffer e = new StringBuffer("abc");

         e.append(true);

         //删除指定index 位置的字符

         StringBuffer f = new StringBuffer("abc");

         f.deleteCharAt();

         //删除指定区间的字符

         StringBuffer g = new StringBuffer("abcdefghjjkl");

         g.delete(,);

         //在index 位置插入字符串或者字符

         StringBuffer h = new StringBuffer("huhhhuhuhuhhh");

         String tmp = "njjjjjjj";

         char ch = 'c';

         h.insert(,ch);

         h.insert(,tmp);

         //字符串反转

         StringBuffer j = new StringBuffer("");

         j.reverse();

         //替换字符串

         StringBuffer i = new StringBuffer("");

         i.replace(, , "ab");//左闭右开

         //子串

         StringBuffer kk = new StringBuffer("");

         String kk1 = kk.substring();//返回下标开始以后的字符串

         String kk2 = kk.substring(,);//l 到 r-1的字符串

         System.out.println(kk1);

         System.out.println(kk2);

    }

 }

巴特西

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