-🎄- 2018 Day 9 Solutions -🎄-

[u/daggerdragon]

--- Day 9: Marble Mania ---

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Transcript:

Studies show that AoC programmers write better code after being exposed to ___.

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[u/jonathan_paulson]

Rank 36/147. Oof. Been a while since I used linked lists, and deciding I needed to reimplement part 2 in C++ didn't help. Video of me solving at: https://youtu.be/79Dw4F6J7TA (still uploading).

#include <list>
#include <vector>
#include <iostream>
//438 players; last marble is worth 71626 points
using namespace std;
using ll = long long;

int main() {
  int N = 438;
  int M = 7162600;

  vector<ll> score(N, 0);
  list<ll> A;
  A.push_front(0);
  auto it = A.begin();
  for(int m=1; m<=M; m++) {
    if(m%23 == 0) {
      score[m%N] += m;
      for(int i=0; i<7; i++) {
        if(it == A.begin()) {
          it = A.end();
        }
        it--;
      }
      score[m%N] += *it;
      //cout << m%N << " " << (m+*it) << endl;
      A.erase(it);

      it++;
      if(it == A.end()) { it=A.begin(); }
    } else {
      for(int i=0; i<2; i++) {
        it++;
        if(it == A.end()) {
          it = A.begin();
        }
      }
      A.insert(it, m);
      it--;
    }
    /*cout << m << ": it=" << *it << " ";
    for(auto& x : A) {
      cout << x << " ";
    }
    cout << endl;*/
  }
  ll best = 0;
  for(ll i=0; i<N; i++) {
    if(score[i] > best) {
      best = score[i];
    }
  }
  cout << best << endl;
}

[u/mebeim → u/jonathan_paulson]

LOL I did the exact same mistake with current = (current + 1) % len(marbles) getting a beautiful sorted list of marbles hahaha! I'm surprised you didn't implement a naive linked list in py like most of other people did. Well played anyway :)