Friday, January 20, 2012

Factorial and Fibonacci in Groovy



Here below a little program in Groovy that implements 2 classes (in fact, they are 3 + an extra utility Stopwatch class from my previous post http://carlosqt.blogspot.com/2011/05/stopwatch-class-for-java.html). There is the main class, called Fiborial (Fibo(nnacci)+(Facto)rial) that implements the Fibonacci and the Factorial algorithms in two ways, one Recursive (using recursion) and the other Imperative (using loops and states). The second class is just an instance class that does the same thing, but its there just to show the difference between static and instance classes, and finally the third one (which will not appear in other languages) is the Program class which has the static execution method "main".

You can also find 3 more little examples at the bottom. One prints out the Factorial's Series and Fibonacci's Series, the second one just shows a class that mixes both: static and instance members, and finally the third one that uses different return types (including java.math.BigInteger) for the Factorial method to compare the timing and result.

As with the previous posts, you can copy and paste the code below in your favorite IDE/Editor and start playing and learning with it. This little "working" program will teach you some more basics of the Programming Language.

There are some "comments" on the code added just to tell you what are or how are some features called. In case you want to review the theory, you can read my previous post, where I give a definition of each of the concepts mentioned on the code. You can find it here: http://carlosqt.blogspot.com/2011/01/new-series-factorial-and-fibonacci.html 


The Fiborial Program

// Factorial and Fibonacci in Groovy  
package com.series  
import java.math.BigInteger  
  
// Instance Class  
class StaticFiborial    
{      
    // Static Field      
    private static className  
    // Class/Static Constructor/Initializer    
    static    
    {      
        className = "Static Constructor"  
        println className  
    }      
    // Class/Static Method - Factorial Recursive      
    static factorialR(int n)      
    {      
        if (n == 1)      
            return BigInteger.ONE  
        else      
            return n * factorialR(n - 1)  
    }      
    // Class/Static Method - Factorial Imperative      
    static factorialI(int n)      
    {      
        def res = BigInteger.ONE  
        for (int i = n; i >= 1; i--)      
        {                      
            res *= i  
        }      
        return res  
    }      
    // Class/Static Method - Fibonacci Recursive      
    static fibonacciR(int n)      
    {      
        if (n < 2)      
            return 1  
        else      
            return fibonacciR(n - 1) + fibonacciR(n - 2)  
    }      
    // Class/Static Method - Fibonacci Imperative      
    static fibonacciI(int n)      
    {                  
        def pre, cur, tmp = 0  
        pre = cur = 1          
        for (i in 2..n)  
        {      
            tmp = cur + pre  
            pre = cur  
            cur = tmp  
        }      
        return cur    
    }          
    // Class/Static Method - Benchmarking Algorithms      
    static benchmarkAlgorithm(algorithm, values)      
    {                  
        def timer = new Stopwatch()  
        def i, testValue  
        def facTimeResult = BigInteger.ZERO  
        def fibTimeResult = 0  
        i = testValue = 0              
              
        // "Switch" Flow Control Statement      
        switch (algorithm)      
        {      
            case 1:      
                println "\nFactorial Imperative:"  
                // "For" Loop Statement      
                for (i = 0; i < values.size(); i++)      
                {                              
                    testValue = ((Integer)values.get(i)).intValue()  
                    // Taking Time      
                    timer.start()  
                    facTimeResult = factorialI(testValue)  
                    timer.stop()      
                    // Getting Time      
                    println " ($testValue) = ${timer.getElapsed()}"  
                }                          
                break      
            case 2:      
                println "\nFactorial Recursive:"  
                // "While" Loop Statement      
                while (i < values.size())      
                {                              
                    testValue = ((Integer)values.get(i)).intValue()  
                    // Taking Time      
                    timer.start()  
                    facTimeResult = factorialR(testValue)  
                    timer.stop()  
                    // Getting Time      
                    println " ($testValue) = ${timer.getElapsed()}"  
                    i++  
                }      
                break     
            case 3:      
                println "\nFibonacci Imperative:"  
                // "For" Loop Statement      
                for (j in 0..values.size()-1)  
                {   
                    testValue = ((Integer)values.get(j)).intValue()  
                    // Taking Time  
                    timer.start()  
                    fibTimeResult = fibonacciI(testValue)  
                    timer.stop()  
                    // Getting Time      
                    println " ($testValue) = ${timer.getElapsed()}"                      
                }                  
                break  
            case 4:      
                println "\nFibonacci Recursive:"  
                // "For Each" Loop Statement                      
                for (item in values)  
                {      
                    testValue = item  
                    // Taking Time      
                    timer.start()    
                    fibTimeResult = fibonacciR(testValue)  
                    timer.stop()  
                    // Getting Time  
                    println " ($testValue) = ${timer.getElapsed()}"  
                }   
                break  
            default:      
                println "DONG!"  
                break  
        }   
    }      
}  
  
// Instance Class      
class InstanceFiborial      
{      
    // Instance Field      
    private def className  
    // Instance Constructor      
    def InstanceFiborial()      
    {      
        this.className = "Instance Constructor"  
        println this.className  
    }      
    // Instance Method - Factorial Recursive      
    def factorialR(n)      
    {      
        // Calling Static Method      
        return StaticFiborial.factorialR(n)  
    }      
    // Instance Method - Factorial Imperative      
    def factorialI(n)      
    {      
        // Calling Static Method      
        return StaticFiborial.factorialI(n)      
    }      
    // Instance Method - Fibonacci Recursive  
    def fibonacciR(n)      
    {      
        // Calling Static Method      
        return StaticFiborial.fibonacciR(n)  
    }      
    // Instance Method - Factorial Imperative      
    def fibonacciI(n)      
    {      
        // Calling Static Method      
        return StaticFiborial.fibonacciI(n)  
    }      
}    
  
  
println "\nStatic Class"      
// Calling Static Class and Methods  
// No instantiation needed. Calling method directly from the class      
println "FacImp(5) = ${StaticFiborial.factorialI(5)}"  
println "FacRec(5) = ${StaticFiborial.factorialR(5)}"      
println "FibImp(11)= ${StaticFiborial.fibonacciI(11)}"      
println "FibRec(11)= ${StaticFiborial.fibonacciR(11)}"  
  
println "\nInstance Class"      
// Calling Instance Class and Methods       
// Need to instantiate before using. Calling method from instantiated object      
def ff = new InstanceFiborial()  
println "FacImp(5) = ${ff.factorialI(5)}"  
println "FacRec(5) = ${ff.factorialR(5)}"  
println "FibImp(11)= ${ff.fibonacciI(11)}"  
println "FibRec(11)= ${ff.fibonacciR(11)}"  
  
// Create a list of integer values to test  
// From 5 to 50 by 5      
def values = []  
5.step(55, 5) {  
    values.add(it)  
}  
  
// Benchmarking Fibonacci                           
// 1 = Factorial Imperative                  
StaticFiborial.benchmarkAlgorithm(1, values)  
// 2 = Factorial Recursive      
StaticFiborial.benchmarkAlgorithm(2, values)  
  
// Benchmarking Factorial                  
// 3 = Fibonacci Imperative      
StaticFiborial.benchmarkAlgorithm(3, values)  
// 4 = Fibonacci Recursive      
StaticFiborial.benchmarkAlgorithm(4, values)  
  
// Stop and exit      
println "Press any key to exit..."    
def sin = new Scanner(System.in)    
def line = sin.nextLine()    
sin.close()

And the Output is:























































Printing the Factorial and Fibonacci Series
package com.series  
import java.math.BigInteger    
import java.lang.StringBuffer  
    
class Fiborial    
{    
    // Using a StringBuffer as a list of string elements    
    static getFactorialSeries(n)    
    {    
        // Create the String that will hold the list    
        def series = new StringBuffer()  
        // We begin by concatenating the number you want to calculate    
        // in the following format: "!# ="    
        series.append("!")  
        series.append(n)  
        series.append(" = ")  
        // We iterate backwards through the elements of the series    
        for (i in n..0)  
        {    
            // and append it to the list    
            series.append(i)  
            if (i > 1)  
                series.append(" * ")  
            else     
                series.append(" = ")  
        }  
        // Get the result from the Factorial Method    
        // and append it to the end of the list    
        series.append(factorial(n))    
        // return the list as a string    
        return series
    }    
    
    // Using a StringBuffer as a list of string elements    
    static getFibonnaciSeries(n)    
    {    
        // Create the String that will hold the list    
        def series = new StringBuffer();    
        // We begin by concatenating the first 3 values which    
        // are always constant    
        series.append("0, 1, 1")  
        // Then we calculate the Fibonacci of each element    
        // and add append it to the list    
        for (i in 2..n)  
        {    
            if (i < n)    
                series.append(", ")  
            else    
                series.append(" = ")  
                
            series.append(fibonacci(i))  
        }    
        // return the list as a string    
        return series    
    }    
    
    static factorial(n)    
    {    
        if (n == 1)      
            return BigInteger.ONE  
        else      
            return n * factorial(n - 1)  
    }            
    
    static fibonacci(n)    
    {    
        if (n < 2)      
            return 1  
        else      
            return fibonacci(n - 1) + fibonacci(n - 2)  
    }       
}    
  
  
// Printing Factorial Series    
println ""
println Fiborial.getFactorialSeries(5)    
println Fiborial.getFactorialSeries(7)  
println Fiborial.getFactorialSeries(9)  
println Fiborial.getFactorialSeries(11)  
println Fiborial.getFactorialSeries(40)  
// Printing Fibonacci Series    
println ""  
println Fiborial.getFibonnaciSeries(5)  
println Fiborial.getFibonnaciSeries(7)  
println Fiborial.getFibonnaciSeries(9)  
println Fiborial.getFibonnaciSeries(11)  
println Fiborial.getFibonnaciSeries(40)

And the Output is:
















Mixing Instance and Static Members in the same Class

Instance classes can contain both, instance and static members such as: fields, getters/setters, constructors/initializers, methods, etc.

package com.series

// Instance Class    
class Fiborial    
{    
    // Instance Field    
    private def instanceCount    
    // Static Field    
    private static staticCount
    // Instance Read-Only Getter    
    // Within instance members, you can always use      
    // the "this" reference pointer to access your (instance) members.    
    def getInstanceCount()  
    {    
        return this.instanceCount     
    }    
    // Static Read-Only Getter        
    // As with Static Methods, you cannot reference your class members    
    // with the "this" reference pointer since static members are not    
    // instantiated.            
    static getStaticCount()  
    {    
        return staticCount    
    }    
    // Instance Constructor    
    def Fiborial()    
    {    
        this.instanceCount = 0
        println "\nInstance Constructor ${this.instanceCount}"
    }    
    // Static Constructor    
    static
    {    
        staticCount = 0;    
        println "\nStatic Constructor $staticCount"    
    }    
  
    // Instance Method    
    def factorial(n)    
    {    
        this.instanceCount += 1
        println "\nFactorial($n)"
    }    
  
    // Static Method    
    static fibonacci(n)    
    {    
        staticCount += 1    
        println "\nFibonacci($n)"
    }                    
}  

// Calling Static Constructor and Methods    
// No need to instantiate    
Fiborial.fibonacci(5)

// Calling Instance Constructor and Methods
// Instance required    
def fib = new Fiborial()
fib.factorial(5)           

Fiborial.fibonacci(15)
fib.factorial(5)

// Calling Instance Constructor and Methods    
// for a second object    
def fib2 = new Fiborial()
fib2.factorial(5)

println ""
// Calling Static Property    
println "Static Count = ${Fiborial.getStaticCount()}}"
// Calling Instance Property of object 1 and 2    
println "Instance 1 Count = ${fib.getInstanceCount()}"
println "Instance 2 Count = ${fib2.getInstanceCount()}"

And the Output is:



















Factorial using java.lang.Long, java.lang.Double, java.math.BigInteger


package com.series    
import java.math.BigInteger  
      
// Long Factorial      
long factorialInt64(n)      
{      
    if (n == 1)      
        return 1    
    else      
        return n * factorialInt64(n - 1)    
}    
  
// Double Factorial    
double factorialDouble(n)      
{      
    if (n == 1)      
        return 1  
    else      
        return n * factorialDouble(n - 1)  
}    
  
// BigInteger Factorial     
BigInteger factorialBigInteger(n)      
{      
    if (n == 1)      
        return BigInteger.ONE  
    else      
        return n * factorialBigInteger(n - 1)
}    
  
def timer = new Stopwatch()  
long facIntResult = 0     
double facDblResult = 0  
def facBigResult = BigInteger.ZERO      
  
println "\nFactorial using Int64"  
// Benchmark Factorial using Int64      
for (i in (5..50).step(5)) {      
    timer.start()  
    facIntResult = factorialInt64(i)  
    timer.stop()      
    println " ($i) = ${timer.getElapsed()} : ${facIntResult}"    
}      
println "\nFactorial using Double"  
// Benchmark Factorial using Double      
for (i in (5..50).step(5)) {      
    timer.start()  
    facDblResult = factorialDouble(i)  
    timer.stop()  
    println " ($i) = ${timer.getElapsed()} : ${facDblResult}"  
}      
println "\nFactorial using BigInteger"  
// Benchmark Factorial using BigInteger      
for (i in (5..50).step(5)) {      
    timer.start()  
    facBigResult = factorialBigInteger(i)  
    timer.stop()  
    println " ($i) = ${timer.getElapsed()} : ${facBigResult}"              
}

And the Output is:


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