fannkuch-redux Toit #8 program

/* The Computer Language Benchmarks game
   https://salsa.debian.org/benchmarksgame-team/benchmarksgame/

   Naive transliteration from Rex Kerr's Scala program
   contributed by Isaac Gouy
*/

fannkuch n/int -> int:
   perm1 := List n
   n.repeat: perm1[it] = it
   perm := List n
   count := List n   
   f := 0; flips := 0; nperm := 0; checksum := 0; j := 0; k := 0; r := 0

   r = n
   while r > 0:   
      i := 0   
      while r != 1: count[r - 1] = r; r -= 1    
      while i < n: perm[i] = perm1[i]; i += 1   
   
      // Count flips and update max and checksum
      f = 0   
      k = perm[0]
      while k != 0:
         i = 0      
         while 2*i < k:      
            t := perm[i]; perm[i] = perm[k - i]; perm[k - i] = t       
            i += 1       
      
         k = perm[0]  
         f += 1
         
      if f > flips: flips = f           
      if (nperm & 0x1) == 0:   
         checksum += f 
      else: 
         checksum -= f         
         
      // Use incremental change to generate another permutation           
      more := true         
      while more:  
         if r == n:
            print checksum                     
            return flips 
            
         p0 := perm1[0]
         i = 0
         while i < r:
            j = i + 1
            perm1[i] = perm1[j]
            i = j
            
         perm1[r] = p0             
      
         count[r] -= 1        
         if count[r] > 0: more = false
         else: r += 1 
         
      nperm += 1

   return flips 
                            
main args:
  n := args.size == 1 ? int.parse args[0] : 7
  print "Pfannkuchen($n) = $(fannkuch n)"    
                  
    

NOTES:
64-bit Ubuntu quad core
v2.0.0-alpha.174



 Fri, 13 Dec 2024 00:32:33 GMT

MAKE:
cp -r Include/toit/.packages .
cp -r Include/toit/package.lock .
cp -r Include/toit/package.yaml .	
/opt/src/toit/bin/toit.compile -O2 --strip -o fannkuchredux.toit-8.toit_run fannkuchredux.toit-8.toit 

1.20s to complete and log all make actions

COMMAND LINE:
 ./fannkuchredux.toit-8.toit_run 12

PROGRAM OUTPUT:
3968050
Pfannkuchen(12) = 65