Java Java Java

学下java 的大数该怎么用><

hdu 1023 Train Problem II

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);
    }
 }