// Generate random permutation of n integers.
// After http://cap-lore.com/code/ocaml/misc.ml
#include <stdlib.h>
#define C const
static char C * C a = "0123456789abcdef";
void rp(int n, char ans[n]){
  char ra[n]; {int j=n; while(j--) ra[j]=j;}
  {int i=n; while(i--){
     int f = random()%(i+1); ans[i] = *(a+ra[f]); ra[f] = ra[i];}}}

typedef unsigned long int P;
#include <string.h>
#include <stdio.h>
static P cn = 0, cx=0;
static P sw[] = {0x0123456789ABCDEF, 0x021346578A9BCEDF,
0x041526378C9DAEBF, 0x08192A3B4C5D6E7F, 0x123C485A697BDE,
0X14283A596C7DBE, 0X24356879ACBD, 0X36587A9C, 0X3456789ABC, 0};

int main(){int w=100000000; while(w--) {char y[17]; char u[16]; rp(16, y);
memcpy(u, y, 16); y[16]=0;
P * c = sw; while(*c){P p = *(c++); while(p){int k = p&15, i = (p>>4)&15;
    if(u[i]>u[k]){char t = u[i]; u[i] = u[k]; u[k] = t;} p >>= 8;}}
if(memcmp(u, a, 16)) {if(0) ++cn; else {
{for(int j = 0; j<16; ++j) printf ("%c%c%c ", u[j], y[j], a[j]);}
exit(printf("Foo\n"));}}
if(!(cx++& ((1L<<20)-1)))printf("%s %ld %ld\n", y, cx>>20, cn);}
return 0;}