Advent of Code 2022 Day 15

aoc_day15_sensors.cpp

#include <bits/stdc++.h>

struct p {int x, y; p(int ax, int ay) : x(ax), y(ay) {} p() : x(0), y(0) {} bool operator!=(const p &o) { return x != o.x || y != o.y; } };

std::vector<std::pair<p, int>> read_input();
int distance(p p1, p p2);

int main()
{
  auto sensors_and_distances = read_input();
  const int idx = 6;

  auto sensor = sensors_and_distances[idx].first;
  int d = sensors_and_distances[idx].second;

  /*
  std::cout << sensor.x-d-1 << ' ' << sensor.y << '\n';
  std::cout << sensor.x << ' ' << sensor.y-d-1 << '\n';
  std::cout << sensor.x+d+1 << ' ' << sensor.y << '\n';
  std::cout << sensor.x << ' ' << sensor.y+d+1 << '\n';
  */

  const std::vector<p> deltas{{+1, -1}, {+1, +1}, {-1, +1}, {-1, -1}};
  int jdx = 0;
  p cur(sensor.x-d-1, sensor.y);
  const std::vector<p> next{{sensor.x, sensor.y-d-1}, {sensor.x+d+1, sensor.y}, {sensor.x, sensor.y+d+1}, {sensor.x-d-1, sensor.y}};
  while(jdx < 4)
  {
    while(cur != next[jdx])
    {
      //std::cout << cur.x << ' ' << cur.y << ' ' << next[jdx].x << ' ' << next[jdx].y << '\n';
      cur.x += deltas[jdx].x;
      cur.y += deltas[jdx].y;

      bool possible = true;
      for(int i = 0; i<static_cast<int>(sensors_and_distances.size()) && possible; i++)
      {
        if(i == idx) continue;
        if(distance(cur, sensors_and_distances[i].first) <= sensors_and_distances[i].second) possible = false;
      }

      if(possible) std::cout << cur.x << ' ' << cur.y << ' ' << 4000000*static_cast<long long>(cur.x) + cur.y << '\n';
    }

    jdx++;
  }
}

int distance(p p1, p p2)
{
  return std::abs(p1.x-p2.x) + std::abs(p1.y-p2.y);
}

std::vector<std::pair<p, int>> read_input()
{
  std::string str;
//  std::set<int> set;
  std::vector<std::pair<p, int>> sensors_and_distances;
  while(std::getline(std::cin, str))
  {
    std::istringstream ss(str);
    std::string Sensor, at, colon, closest, beacon, is, comma;
    p s, b;
    char c, eq;
    ss >> Sensor >> at >> c >> eq  >> s.x >> comma >> c >> eq >> s.y >> colon
       >> closest >> beacon >> is >> at >> c >> eq >> b.x >> comma >> c >> eq >> b.y;
    assert(Sensor=="Sensor"); assert(at=="at"); assert(eq=='=');
    //std::cout << s.x << ' ' << s.y << ' ' << b.x << ' ' << b.y << std::endl;
    sensors_and_distances.push_back(std::make_pair(s, distance(s, b)));
  }

  return sensors_and_distances;
}