Java番石榴 | IntMath 类的 pow(int b, int k) 方法

Guava 的 IntMath 类的方法pow(int b, int k)返回b 的 k 次方。即使结果溢出，它也会等于 BigInteger.valueOf(b).pow(k).intValue()。此实现在O(log k)时间内运行。

句法：

public static int pow(int b, int k)

异常：如果 k < 0，方法 pow(int b, int k) 将抛出IllegalArgumentException 。

示例 1：

// Java code to show implementation of
// pow(int b, int k) method of Guava's
// IntMath class
  
import java.math.RoundingMode;
import com.google.common.math.IntMath;
  
class GFG {
  
    static int findPow(int b, int k)
    {
  
        // Using pow(int b, int k)
        // method of Guava's IntMath class
        int ans = IntMath.pow(b, k);
  
        // Return the answer
        return ans;
    }
  
    // Driver code
    public static void main(String args[])
    {
        int b = 4;
        int k = 5;
  
        int ans = findPow(b, k);
  
        System.out.println(b + " to the " + k
                           + "th power is: "
                           + ans);
  
        b = 12;
        k = 3;
  
        ans = findPow(b, k);
  
        System.out.println(b + " to the " + k
                           + "th power is: "
                           + ans);
    }
}

输出：

4 to the 5th power is: 1024
12 to the 3th power is: 1728

示例 2：

// Java code to show implementation of
// pow(int b, int k) method of Guava's
// IntMath class
import java.math.RoundingMode;
import com.google.common.math.IntMath;
  
class GFG {
  
    static int findPow(int b, int k)
    {
  
        try {
            // Using pow(int b, int k)
            // method of Guava's IntMath class
            // This should throw "IllegalArgumentException"
            // as k < 0
            int ans = IntMath.pow(b, k);
  
            // Return the answer
            return ans;
        }
        catch (Exception e) {
            System.out.println(e);
            return -1;
        }
    }
  
    // Driver code
    public static void main(String args[])
    {
        int b = 4;
        int k = -5;
  
        try {
            // Using pow(int b, int k)
            // method of Guava's IntMath class
            // This should throw "IllegalArgumentException"
            // as k < 0
            IntMath.pow(b, k);
        }
        catch (Exception e) {
            System.out.println(e);
        }
    }
}

输出：

java.lang.IllegalArgumentException: exponent (-5) must be >= 0

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