Java 大数

常规运算 

package class1;
import java.math.BigInteger;
import java.util.*;
public class Big {

  public static void main(String[] args) {
    // TODO Auto-generated method stub
    Scanner cin = new Scanner(System.in) ; 
    BigInteger a ,b ,c ,d ; 
    BigInteger ans_add , ans_sub , ans_mul , ans_div ,ans_mod ; 
    a = cin.nextBigInteger() ; 
    b = cin.nextBigInteger() ;
    ans_add = a.add(b) ; 
    ans_sub = a.subtract(b) ;
    ans_mul = a.multiply(b)  ;
    ans_div = a.divide(b) ; 
    ans_mod = a.mod(b) ;
    System.out.println("a + b = " +ans_add);
    System.out.println("a - b = " +ans_sub);
    System.out.println("a * b = " +ans_mul);
    System.out.println("a / b = " +ans_div);
    System.out.println("a % b = " +ans_mod);
    if(a.compareTo(b)==0 ){ // 比较
      System.out.println("相等");
    }
    else {
      
      System.out.println("不相等");
    }
    

  }

}

多个数连续相加，遇到0就停止相加，给出结果

package class1;
import java.math.BigInteger;
import java.util.*;
public class Big {

  public static void main(String[] args) {
    // TODO Auto-generated method stub
    Scanner cin = new Scanner(System.in) ; 
    BigInteger x = BigInteger.valueOf(0);  // 初始化
    BigInteger ans = BigInteger.valueOf(0); 
    BigInteger y = BigInteger.valueOf(0) ; 
    while(cin.hasNext()) {
      x = cin.nextBigInteger() ; 
      if(x.equals(y)) {
        break ; 
      }
      ans = ans.add(x) ; 
    }
    System.out.println(ans);
  }

}

计算卡特兰数 

import java.math.BigInteger;
import java.util.*;
public class Big2 {

  public static void main(String[] args) {
    // TODO Auto-generated method stub
    // h(n)=h(n-1)*(4*n-2)/(n+1);
    Scanner cin = new Scanner(System.in) ; 
    BigInteger dp[] = new BigInteger[110] ; 
    dp[1] = BigInteger.valueOf(1) ; 
    for(int i = 2 ; i<= 10 ; i++ ) {
      dp[i] = dp[i-1].multiply(BigInteger.valueOf(4*i-2)).divide(BigInteger.valueOf(i+1)) ; 
    }
    for(int i = 1 ; i<=10 ; i++ ) {
      System.out.println(" " +dp[i]);
    }
    
  }

}