#include "aoc.h"

namespace aoc2017 {

static spinlock* next(spinlock* x, int step) {
  while (step-- > 0) {
    x = x->next;
  }
  return x;
}

static void insert(spinlock* s, spinlock** current, int v) {
  spinlock* n = s->next;
  spinlock* x = new spinlock;
  x->val = v;
  s->next = x;
  x->prev = s;
  x->next = n;
  n->prev = x;
  *current = x;
}

std::pair<int64_t, int64_t> day17(line_view file) {
  spinlock* l = new spinlock;
  l->val = 0;
  l->next = l;
  l->prev = l;
  // spinlock* l0 = l;

  int step{356};
  for (int i = 1; i < 2018; i++) {
    l = next(l, step);
    insert(l, &l, i);
  }
  int t0 = l->next->val;
  // printf("%d\n", l0->next->val);

  return {t0, 0};
}

} // namespace aoc2017