Java Guava BigIntegerMath binomial()用法及代码示例

Guava BigIntegerMath类的二项式(int n，int k)方法返回n选择k，也称为n和k的二项式系数，即

n! / (k! (n - k)!)

用法:

public static BigInteger binomial(int n, int k)

参数：此方法采用以下参数：

n：二项式展开的基础。
k：二项式展开的力量。

返回值：此方法返回n和k的二项式系数。

异常：如果n <0，k <0或k> n，则此方法引发IllegalArgumentException。

注意：结果可能占用O(k log n)个空间。

以下示例说明了BifIntegerMath.binomial()方法：

范例1：

// Java code to show implementation of 
// binomial(int n, int k) method 
// of Guava's BigIntegerMath class 
  
import java.math.*; 
import com.google.common.math.BigIntegerMath; 
  
class GFG { 
  
    // Driver code 
    public static void main(String args[]) 
    { 
        int n = 5; 
        int k = 2; 
  
        // Using binomial(int n, int k) method of 
        // Guava's BigIntegerMath class 
        BigInteger ans = BigIntegerMath.binomial(n, k); 
  
        System.out.println("Binomial Coefficient of "
                           + n + " & " + k 
                           + " is:" + ans); 
  
        int n1 = 15; 
        int k1 = 9; 
  
        // Using binomial(int n, int k) method of 
        // Guava's BigIntegerMath class 
        BigInteger ans1 = BigIntegerMath.binomial(n1, k1); 
  
        System.out.println("Binomial Coefficient of "
                           + n1 + " & " + k1 
                           + " is:" + ans1); 
    } 
}

输出：

Binomial Coefficient of 5 & 2 is:10
Binomial Coefficient of 15 & 9 is:5005

范例2：

// Java code to show implementation of 
// binomial(int n, int k) method 
// of Guava's BigIntegerMath class 
  
import java.math.*; 
import com.google.common.math.BigIntegerMath; 
  
class GFG { 
  
    // Driver code 
    public static void main(String args[]) 
    { 
  
        try { 
            int n = 5; 
            int k = 7; 
  
            // Using binomial(int n, int k) method of 
            // Guava's BigIntegerMath class 
            // This should raise "IllegalArgumentException" 
            // as k > n 
            BigInteger ans = BigIntegerMath.binomial(n, k); 
  
            System.out.println("Binomial Coefficient of"
                               + n + " & " + k 
                               + " is:" + ans); 
        } 
        catch (Exception e) { 
            System.out.println("Exception:" + e); 
        } 
    } 
}

输出：

Exception:java.lang.IllegalArgumentException:k (7) > n (5)

参考： https://google.github.io/guava/releases/21.0/api/docs/com/google/common/math/BigIntegerMath.html#binomial-int-int-

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注：本文由纯净天空筛选整理自Sahil_Bansall大神的英文原创作品 BigIntegerMath binomial() function | Guava | Java。非经特殊声明，原始代码版权归原作者所有，本译文未经允许或授权，请勿转载或复制。