/*

* The Computer Language Benchmarks Game

* http://shootout.alioth.debian.org/

*

* converted to C by Joseph Piché

* from Java version by Oleg Mazurov and Isaac Gouy

*

*/

#include <stdio.h>

#include <stdlib.h>

#include "bench-framework.h"

#include "nvmalloc_wrap.h"

inline static int max(int a, int b)

{

return a > b ? a : b;

}

//n = 10, pf[0] = 73196, pf[1] = 38

//n = 11, pf[0] = 556355, pf[1] = 51

int ref_checksum = 73196;

int ref_flips = 38;

int fannkuchredux(int n)

{

int *perm;

int perm1[n];

int count[n];

int maxFlipsCount = 0;

int permCount = 0;

int checksum = 0;

int i;

perm = (int *)allocate_mem(n);

for (i=0; i<n; i+=1)

perm1[i] = i;

int r = n;

while (1) {

while (r != 1) {

count[r-1] = r;

r -= 1;

}

for (i=0; i<n; i+=1)

perm[i] = perm1[i];

int flipsCount = 0;

int k;

while ( !((k = perm[0]) == 0) ) {

int k2 = (k+1) >> 1;

for (i=0; i<k2; i++) {

int temp = perm[i]; perm[i] = perm[k-i]; perm[k-i] = temp;

}

flipsCount += 1;

}

maxFlipsCount = max(maxFlipsCount, flipsCount);

checksum += permCount % 2 == 0 ? flipsCount : -flipsCount;

/* Use incremental change to generate another permutation */

while (1) {

if (r == n) {

if (n == 10 && checksum != ref_checksum) return -1;

if (n == 10 && maxFlipsCount != ref_flips) return -1;

return 0;

}

int perm0 = perm1[0];

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++;

}

permCount++;

}

}

/*

int main(int argc, char *argv[])

{

int n = argc > 1 ? atoi(argv[1]) : 7;

printf("Pfannkuchen(%d) = %d\n", n, fannkuchredux(n));

return 0;

}

*/

int run_fannkuch(int n) {

return fannkuchredux(n);

}