Groovy example source code file (fannkuch.groovy)

This example Groovy source code file (fannkuch.groovy) is included in the DevDaily.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Java by Example" ^TM.

Java - Groovy tags/keywords

pfannkuchen, pfannkuchen

The Groovy fannkuch.groovy source code

/* The Computer Language Benchmarks Game
   http://shootout.alioth.debian.org/
   contributed by Brian Schlining
*/

def n = 7
if (args.length > 0) {
    n = Integer.parseInt(args[0])
}
println("Pfannkuchen(" + n + ") = " + fannkuch(n))

    
def fannkuch(int n) {
    int check = 0
    int[] perm = new int[n]
    int[] perm1 = new int[n]
    int[] count = new int[n]
    int[] maxPerm = new int[n]
    int maxFlipsCount = 0
    int m = n - 1

    for (i in 0..<n) {
        perm1[i] = i
    }
    int r = n

    while (true) {
        // write-out the first 30 permutations
        if (check < 30){
            for (i in 0..<n) {
                print(perm1[i] + 1)
            }
            print("\n")
            check++
        }

        while (r != 1) { 
            count[r - 1] = r
            r-- 
        }
        if (!(perm1[0] == 0 || perm1[m] == m)) {
            for (i in 0..<n) {
                perm[i] = perm1[i]
            }
            
            int flipsCount = 0
            int k

            while (!((k = perm[0]) == 0)) {
                int k2 = (k + 1) >> 1
                for (i in 0..<k2) {
                    int temp = perm[i] 
                    perm[i] = perm[k - i] 
                    perm[k - i] = temp
                }
                flipsCount++
            }

            if (flipsCount > maxFlipsCount) {
                maxFlipsCount = flipsCount
                for (i in 0..<n) {
                    maxPerm[i] = perm1[i]
                }
            }
        }

        while (true) {
            if (r == n) {
                return maxFlipsCount
            }
            int perm0 = perm1[0]
            int i = 0
            while (i < r) {
                int j = i + 1
                perm1[i] = perm1[j]
                i = j
            }
            perm1[r] = perm0

            count[r] = count[r] - 1
            if (count[r] > 0) {
                break
            }
            r++
        }
    }
}