var fannkuch = function(n)
{
var p = [], q = [], s = [], sign = 1, maxflips = 0, sum = 0;
var i;
for(i=1; i<=n; i++) p[i] = q[i] = s[i] = i;
for(;;){
// Copy and flip.
var q1 = p[1]; // Cache 1st element.
if(q1 != 1){
for(i=2; i<=n; i++) q[i] = p[i]; // Work on a copy.
var flips = 1;
for(;;){
var qq = q[q1];
if(qq == 1){ // ... until 1st element is 1.
sum = sum + sign*flips;
if(flips > maxflips){
maxflips = flips;
} // New maximum?
break;
}
q[q1] = q1;
if(q1 >= 4){
var i = 2, j = q1 - 1
for(;;){ var tmp = q[i]; q[i] = q[j]; q[j] = tmp; if(++i >= --j) break; }
}
q1 = qq; flips++;
}
}
// Permute.
if(sign == 1){
var tmp = p[2]; p[2] = p[1]; p[1] = tmp; sign = -1; // Rotate 1<-2.
}else{
var tmp = p[2]; p[2] = p[3]; p[3] = tmp; sign = 1; // Rotate 1<-2 and 1<-2<-3.
for(i = 3;; i++){
// print "mark 4"
var sx = s[i];
if(sx != 1){ s[i] = sx-1; break; }
if(i == n) return [sum, maxflips]; // Out of permutations.
s[i] = i;
// Rotate 1<-...<-i+1.
var t = p[1]; for(var j = 1; j <= i; j++){ p[j] = p[j+1]; } p[i+1] = t;
}
}
}
}
function getTimeSec(){
var d = new Date();
return (d.getTime() + d.getMilliseconds() / 1000.0) / 1000.0;
}
var n = 10;
var start_time = getTimeSec();
var r = fannkuch(n);
var sum = r[0], flips = r[1];
WScript.Echo(
sum,"\n",
"Pfannkuchen(",n,") = ",flips,"\n",
"time = ",(getTimeSec() - start_time),"\n"
)