com.google.common.math.IntMath
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java.lang.Object
@Beta @GwtCompatible(emulated=true) public final class IntMath
A class for arithmetic on values of type int. Where possible, methods are defined and
named analogously to their BigInteger counterparts.
The implementations of many methods in this class are based on material from Henry S. Warren, Jr.'s Hacker's Delight, (Addison Wesley, 2002).
Similar functionality for long and for BigInteger can be found in
LongMath and BigIntegerMath respectively. For other common operations on
int values, see Ints.
| Method Summary | |
|---|---|
static int |
binomial(int n,
int k)
Returns n choose k, also known as the binomial coefficient of n and
k, or Integer.MAX_VALUE if the result does not fit in an int. |
static int |
checkedAdd(int a,
int b)
Returns the sum of a and b, provided it does not overflow. |
static int |
checkedMultiply(int a,
int b)
Returns the product of a and b, provided it does not overflow. |
static int |
checkedPow(int b,
int k)
Returns the b to the kth power, provided it does not overflow. |
static int |
checkedSubtract(int a,
int b)
Returns the difference of a and b, provided it does not overflow. |
static int |
divide(int p,
int q,
RoundingMode mode)
Returns the result of dividing p by q, rounding using the specified
RoundingMode. |
static int |
factorial(int n)
Returns n!, that is, the product of the first n positive
integers, 1 if n == 0, or Integer.MAX_VALUE if the
result does not fit in a int. |
static int |
gcd(int a,
int b)
Returns the greatest common divisor of a, b. |
static boolean |
isPowerOfTwo(int x)
Returns true if x represents a power of two. |
static int |
log10(int x,
RoundingMode mode)
Returns the base-10 logarithm of x, rounded according to the specified rounding mode. |
static int |
log2(int x,
RoundingMode mode)
Returns the base-2 logarithm of x, rounded according to the specified rounding mode. |
static int |
mod(int x,
int m)
Returns x mod m. |
static int |
pow(int b,
int k)
Returns b to the kth power. |
static int |
sqrt(int x,
RoundingMode mode)
Returns the square root of x, rounded with the specified rounding mode. |
| Methods inherited from class java.lang.Object |
|---|
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait |
| Method Detail |
|---|
public static boolean isPowerOfTwo(int x)
true if x represents a power of two.
This differs from Integer.bitCount(x) == 1, because
Integer.bitCount(Integer.MIN_VALUE) == 1, but Integer.MIN_VALUE is not a power
of two.
@GwtIncompatible(value="need BigIntegerMath to adequately test")
public static int log2(int x,
RoundingMode mode)
x, rounded according to the specified rounding mode.
IllegalArgumentException - if x <= 0
ArithmeticException - if mode is RoundingMode.UNNECESSARY and x
is not a power of two
@GwtIncompatible(value="need BigIntegerMath to adequately test")
public static int log10(int x,
RoundingMode mode)
x, rounded according to the specified rounding mode.
IllegalArgumentException - if x <= 0
ArithmeticException - if mode is RoundingMode.UNNECESSARY and x
is not a power of ten
@GwtIncompatible(value="failing tests")
public static int pow(int b,
int k)
b to the kth power. Even if the result overflows, it will be equal to
BigInteger.valueOf(b).pow(k).intValue(). This implementation runs in O(log k)
time.
Compare checkedPow(int, int), which throws an ArithmeticException upon overflow.
IllegalArgumentException - if k < 0
@GwtIncompatible(value="need BigIntegerMath to adequately test")
public static int sqrt(int x,
RoundingMode mode)
x, rounded with the specified rounding mode.
IllegalArgumentException - if x < 0
ArithmeticException - if mode is RoundingMode.UNNECESSARY and
sqrt(x) is not an integer
@GwtIncompatible(value="failing tests")
public static int divide(int p,
int q,
RoundingMode mode)
p by q, rounding using the specified
RoundingMode.
ArithmeticException - if q == 0, or if mode == UNNECESSARY and a
is not an integer multiple of b
public static int mod(int x,
int m)
x mod m. This differs from x % m in that it always returns a
non-negative result.
For example:
mod(7, 4) == 3
mod(-7, 4) == 1
mod(-1, 4) == 3
mod(-8, 4) == 0
mod(8, 4) == 0
ArithmeticException - if m <= 0
public static int gcd(int a,
int b)
a, b. Returns 0 if
a == 0 && b == 0.
IllegalArgumentException - if a < 0 or b < 0
public static int checkedAdd(int a,
int b)
a and b, provided it does not overflow.
ArithmeticException - if a + b overflows in signed int arithmetic
public static int checkedSubtract(int a,
int b)
a and b, provided it does not overflow.
ArithmeticException - if a - b overflows in signed int arithmetic
public static int checkedMultiply(int a,
int b)
a and b, provided it does not overflow.
ArithmeticException - if a * b overflows in signed int arithmetic
@GwtIncompatible(value="failing tests")
public static int checkedPow(int b,
int k)
b to the kth power, provided it does not overflow.
pow(int, int) may be faster, but does not check for overflow.
ArithmeticException - if b to the kth power overflows in signed
int arithmetic@GwtIncompatible(value="need BigIntegerMath to adequately test") public static int factorial(int n)
n!, that is, the product of the first n positive
integers, 1 if n == 0, or Integer.MAX_VALUE if the
result does not fit in a int.
IllegalArgumentException - if n < 0
@GwtIncompatible(value="need BigIntegerMath to adequately test")
public static int binomial(int n,
int k)
n choose k, also known as the binomial coefficient of n and
k, or Integer.MAX_VALUE if the result does not fit in an int.
IllegalArgumentException - if n < 0, k < 0 or k > n
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