problem_30.groovy

import groovyx.gpars.GParsPool

/**
 * Extract decimals of n in correct order 
 */
def decimals(int n) {
	def returned = []
	while(n>0) {
		returned << n%10
		n/=10
	}
	return returned.reverse()
}

/**
 * Check if number is made of sum of power of fifths from its decimal numbers
 */
boolean isMadeofFifths(def n, def fifths) {
	return n>1 && n==decimals(n).inject(0, { result, i -> result+fifths[i] })
}

@Grab(group="org.codehaus.gpars", module="gpars", version="0.11")
def getRealSumsOfFifths(fifths) {
	GParsPool.withPool {
		// Upper bound not obvious to choose
		def testedNumbers = 1..1000000
		return testedNumbers.findAllParallel { n ->
			return isMadeofFifths(n, fifths)
		}
	}
}

long start = System.currentTimeMillis();

/* presence of 0 is a hack to ensure items are correctly stored) */
fifths = (0..9).collect { it.power(5) }

/* Now come GPars time ! */
builtOfFifth = getRealSumsOfFifths(fifths)

println builtOfFifth.sum()

long end = System.currentTimeMillis();
println "duration "+((end-start)/1000.0)+" s";