Java番石榴 | IntMath 类的 binomial() 方法

Guava的IntMath类的binomial(int n, int k)方法接受n和k两个参数，计算二项式系数的值${n}\choose{k}$ .

如果计算值溢出整数的最大值，则该方法返回 Integer.MAX_VALUE 或换句话说，整数的最大值。

句法 ：

public static int binomial(int n, int k)

参数：此方法接受两个参数n和k并计算二项式系数的值${n}\choose{k}$ .

返回值：该方法返回 n 和 k 的二项式系数。

异常：如果 n < 0、k < 0 或 k > n，方法 binomial(int n, int k) 将抛出IllegalArgumentException 。

下面的例子说明了 IntMath 类的 binomial() 方法：

示例 1：

// Java code to show implementation of
// binomial(int n, int k) method of Guava's
// IntMath class
import java.math.RoundingMode;
import com.google.common.math.IntMath;
  
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 IntMath class
        int ans = IntMath.binomial(n, k);
  
        System.out.println("Binomial Coefficient of " + n 
                              + " and " + k + " is : " + ans);
  
        int n1 = 15;
        int k1 = 9;
  
        // Using binomial(int n, int k) method of
        // Guava's IntMath class
        int ans1 = IntMath.binomial(n1, k1);
  
        System.out.println("Binomial Coefficient of " + n1 
                             + " and " + k1 + " is : " + ans1);
    }
}

输出：

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

示例 2：

// Java code to show implementation of
// binomial(int n, int k) method of Guava's
// IntMath class
import java.math.RoundingMode;
import com.google.common.math.IntMath;
  
class GFG {
  
    static int findBinomial(int n, int k)
    {
  
        try {
            // Using binomial(int n, int k)
            // method of Guava's IntMath class
            // This should throw "IllegalArgumentException"
            // as k < 0
            int ans = IntMath.binomial(n, k);
  
            // Return the answer
            return ans;
        }
        catch (Exception e) {
            System.out.println(e);
            return -1;
        }
    }
  
    // Driver code
    public static void main(String args[])
    {
        int n = 5;
        int k = 7;
  
        try {
  
            // Function calling
            findBinomial(n, k);
        }
        catch (Exception e) {
            System.out.println(e);
        }
    }
}

输出：

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

参考 ：
https://google.github.io/guava/releases/20.0/api/docs/com/google/common/math/IntMath.html#binomial-int-int-