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/* The Computer Language Benchmarks Game
http://shootout.alioth.debian.org/
contributed by Isaac Gouy, transliterated from Mike Pall's Lua program
*/
function fannkuch(n) {
var p = Array(n), q = Array(n), s = Array(n);
var sign = 1, maxflips = 0, sum = 0, m = n-1;
for(var i=0; i<n; i++){ p[i] = i; q[i] = i; s[i] = i; }
do {
// Copy and flip.
var q0 = p[0]; // Cache 0th element.
if (q0 != 0){
for(var i=1; i<n; i++) q[i] = p[i]; // Work on a copy.
var flips = 1;
do {
var qq = q[q0];
if (qq == 0){ // ... until 0th element is 0.
sum += sign*flips;
if (flips > maxflips) maxflips = flips; // New maximum?
break;
}
q[q0] = q0;
if (q0 >= 3){
var i = 1, j = q0 - 1, t;
do { t = q[i]; q[i] = q[j]; q[j] = t; i++; j--; } while (i < j);
}
q0 = qq; flips++;
} while (true);
}
// Permute.
if (sign == 1){
var t = p[1]; p[1] = p[0]; p[0] = t; sign = -1; // Rotate 0<-1.
} else {
var t = p[1]; p[1] = p[2]; p[2] = t; sign = 1; // Rotate 0<-1 and 0<-1<-2.
for(var i=2; i<n; i++){
var sx = s[i];
if (sx != 0){ s[i] = sx-1; break; }
if (i == m) return Array(sum,maxflips); // Out of permutations.
s[i] = i;
// Rotate 0<-...<-i+1.
t = p[0]; for(var j=0; j<=i; j++){ p[j] = p[j+1]; } p[i+1] = t;
}
}
} while (true);
}
var n = 10;
var pf = fannkuch(n);
//print(pf[0] + "\n" + "Pfannkuchen(" + n + ") = " + pf[1]);
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