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Add 2018 day 13 cpp
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‎2018/README.md

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@@ -19,7 +19,7 @@ This folder contains solutions to each of the problems in Advent of Code 2018 in
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| <nobr> [Day 10: The Stars Align](https://adventofcode.com/2018/day/10) </nobr> | <nobr> [Part 1](/2018/cpp/day_10a.cpp) [Part 2](/2018/cpp/day_10b.cpp) </nobr> | <nobr> [Part 1](/2018/python/day_10a.py) [Part 2](/2018/python/day_10b.py) </nobr> |[Link](/2018/input/day_10_input)|[Link](/2018/sample_input/day_10_sample_input)|[Link](/2018/puzzles/day_10_puzzle)|
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| <nobr> [Day 11: Chronal Charge](https://adventofcode.com/2018/day/11) </nobr> | <nobr> [Part 1](/2018/cpp/day_11a.cpp) [Part 2](/2018/cpp/day_11b.cpp) </nobr> | <nobr> [Part 1](/2018/python/day_11a.py) [Part 2](/2018/python/day_11b.py) </nobr> |[Link](/2018/input/day_11_input)|[Link](/2018/sample_input/day_11_sample_input)|[Link](/2018/puzzles/day_11_puzzle)|
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| <nobr> [Day 12: Subterranean Sustainability](https://adventofcode.com/2018/day/12) </nobr> | <nobr> [Part 1](/2018/cpp/day_12a.cpp) [Part 2](/2018/cpp/day_12b.cpp) </nobr> | <nobr> [Part 1](/2018/python/day_12a.py) [Part 2](/2018/python/day_12b.py) </nobr> |[Link](/2018/input/day_12_input)|[Link](/2018/sample_input/day_12_sample_input)|[Link](/2018/puzzles/day_12_puzzle)|
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| <nobr> [Day 13: ](https://adventofcode.com/2018/day/13) </nobr> | <nobr> [Part 1](/2018/cpp/day_13a.cpp) [Part 2](/2018/cpp/day_13b.cpp) </nobr> | <nobr> [Part 1](/2018/python/day_13a.py) [Part 2](/2018/python/day_13b.py) </nobr> |[Link](/2018/input/day_13_input)|[Link](/2018/sample_input/day_13_sample_input)|[Link](/2018/puzzles/day_13_puzzle)|
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| <nobr> [Day 13: Mine Cart Madness](https://adventofcode.com/2018/day/13) </nobr> | <nobr> [Part 1](/2018/cpp/day_13a.cpp) [Part 2](/2018/cpp/day_13b.cpp) </nobr> | <nobr> [Part 1](/2018/python/day_13a.py) [Part 2](/2018/python/day_13b.py) </nobr> |[Link](/2018/input/day_13_input)|[Link](/2018/sample_input/day_13_sample_input)|[Link](/2018/puzzles/day_13_puzzle)|
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| <nobr> [Day 14: ](https://adventofcode.com/2018/day/14) </nobr> | <nobr> [Part 1](/2018/cpp/day_14a.cpp) [Part 2](/2018/cpp/day_14b.cpp) </nobr> | <nobr> [Part 1](/2018/python/day_14a.py) [Part 2](/2018/python/day_14b.py) </nobr> |[Link](/2018/input/day_14_input)|[Link](/2018/sample_input/day_14_sample_input)|[Link](/2018/puzzles/day_14_puzzle)|
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| <nobr> [Day 15: ](https://adventofcode.com/2018/day/15) </nobr> | <nobr> [Part 1](/2018/cpp/day_15a.cpp) [Part 2](/2018/cpp/day_15b.cpp) </nobr> | <nobr> [Part 1](/2018/python/day_15a.py) [Part 2](/2018/python/day_15b.py) </nobr> |[Link](/2018/input/day_15_input)|[Link](/2018/sample_input/day_15_sample_input)|[Link](/2018/puzzles/day_15_puzzle)|
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| <nobr> [Day 16: ](https://adventofcode.com/2018/day/16) </nobr> | <nobr> [Part 1](/2018/cpp/day_16a.cpp) [Part 2](/2018/cpp/day_16b.cpp) </nobr> | <nobr> [Part 1](/2018/python/day_16a.py) [Part 2](/2018/python/day_16b.py) </nobr> |[Link](/2018/input/day_16_input)|[Link](/2018/sample_input/day_16_sample_input)|[Link](/2018/puzzles/day_16_puzzle)|

‎2018/cpp/day_13a.cpp

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#include <algorithm>
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#include <array>
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#include <fstream>
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#include <iostream>
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#include <string>
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#include <vector>
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struct Point {
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int x, y;
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Point& operator += (const Point& v) { x += v.x; y += v.y; return *this; }
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Point& operator -= (const Point& v) { x -= v.x; y -= v.y; return *this; }
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};
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bool operator == (const Point& a, const Point& b) { return a.y == b.y && a.x == b.x; }
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bool operator != (const Point& a, const Point& b) { return a.y != b.y || a.x != b.x; }
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bool operator < (const Point& a, const Point& b) { return (a.y != b.y) ? (a.y < b.y) : (a.x < b.x); }
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static constexpr std::array<Point, 4> Dir = {
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Point{ 0, -1 }, // north
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Point{ 1, 0 }, // east
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Point{ 0, 1 }, // south
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Point{ -1, 0 }, // west
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};
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static constexpr int North = 0;
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static constexpr int East = 1;
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static constexpr int South = 2;
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static constexpr int West = 3;
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struct Cart {
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Point pos;
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int dir;
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int next_turn = -1;
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void turn() {
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dir = (dir + 4 + next_turn) & 0x3;
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next_turn = ((next_turn + 2) % 3) - 1;
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}
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void move() {
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pos += Dir[dir];
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}
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};
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bool order_by_pos(const Cart& a, const Cart& b)
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{
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if (a.pos != b.pos)
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return (a.pos < b.pos);
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return (a.dir != b.dir) ? (a.dir < b.dir) : (a.next_turn < b.next_turn);
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}
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struct Map {
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std::vector<std::string> grid;
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std::vector<Cart> carts;
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// Returns index of the first cart which crashed, or -1 if no crashes yet.
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int tick() {
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std::sort(carts.begin(), carts.end(), order_by_pos);
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for (int i = 0; i < carts.size(); i++) {
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carts[i].move();
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switch (grid[carts[i].pos.y][carts[i].pos.x]) {
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case '/': carts[i].dir ^= 1; break;
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case '\\': carts[i].dir ^= 3; break;
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case '+': carts[i].turn(); break;
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default: break;
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}
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for (int j = 0; j < carts.size(); j++) {
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if (j != i && carts[j].pos == carts[i].pos) {
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return i;
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}
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}
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}
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return -1;
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}
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};
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int main(int argc, char* argv[]) {
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std::string input = "../input/day_13_input";
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if (argc > 1) {
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input = argv[1];
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}
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std::ifstream file(input);
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std::string line;
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Map map;
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while (std::getline(file, line)) {
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map.grid.push_back(line);
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}
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Point pos;
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for (pos.y = 0; pos.y < map.grid.size(); pos.y++) {
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for (pos.x = 0; pos.x < map.grid[pos.y].size(); pos.x++) {
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switch (map.grid[pos.y][pos.x]) {
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case '^':
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map.carts.push_back(Cart{ pos, North, -1 });
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map.grid[pos.y][pos.x] = '|';
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break;
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case '>':
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map.carts.push_back(Cart{ pos, East, -1 }); break;
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map.grid[pos.y][pos.x] = '-';
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break;
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case 'v':
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map.carts.push_back(Cart{ pos, South, -1 }); break;
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map.grid[pos.y][pos.x] = '|';
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break;
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case '<':
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map.carts.push_back(Cart{ pos, West, -1 }); break;
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map.grid[pos.y][pos.x] = '-';
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break;
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default:
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break;
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}
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}
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}
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int crashed = map.tick();
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while (crashed == -1) {
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crashed = map.tick();
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}
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std::cout << map.carts[crashed].pos.x << "," << map.carts[crashed].pos.y << '\n';
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return 0;
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}

‎2018/cpp/day_13b.cpp

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#include <algorithm>
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#include <array>
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#include <fstream>
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#include <iostream>
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#include <string>
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#include <vector>
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struct Point {
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int x, y;
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Point& operator += (const Point& v) { x += v.x; y += v.y; return *this; }
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Point& operator -= (const Point& v) { x -= v.x; y -= v.y; return *this; }
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};
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bool operator == (const Point& a, const Point& b) { return a.y == b.y && a.x == b.x; }
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bool operator != (const Point& a, const Point& b) { return a.y != b.y || a.x != b.x; }
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bool operator < (const Point& a, const Point& b) { return (a.y != b.y) ? (a.y < b.y) : (a.x < b.x); }
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static constexpr std::array<Point, 4> Dir = {
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Point{ 0, -1 }, // north
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Point{ 1, 0 }, // east
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Point{ 0, 1 }, // south
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Point{ -1, 0 }, // west
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};
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static constexpr int North = 0;
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static constexpr int East = 1;
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static constexpr int South = 2;
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static constexpr int West = 3;
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struct Cart {
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Point pos;
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int dir;
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int next_turn = -1;
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void turn() {
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dir = (dir + 4 + next_turn) & 0x3;
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next_turn = ((next_turn + 2) % 3) - 1;
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}
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void move() {
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pos += Dir[dir];
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}
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};
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bool order_by_pos(const Cart& a, const Cart& b)
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{
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if (a.pos != b.pos)
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return (a.pos < b.pos);
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return (a.dir != b.dir) ? (a.dir < b.dir) : (a.next_turn < b.next_turn);
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}
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struct Map {
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std::vector<std::string> grid;
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std::vector<Cart> carts;
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// Returns index of the first cart which crashed, or -1 if no crashes yet.
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std::vector<int> tick() {
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std::vector<int> crashed;
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std::sort(carts.begin(), carts.end(), order_by_pos);
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for (int i = 0; i < carts.size(); i++) {
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carts[i].move();
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switch (grid[carts[i].pos.y][carts[i].pos.x]) {
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case '/': carts[i].dir ^= 1; break;
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case '\\': carts[i].dir ^= 3; break;
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case '+': carts[i].turn(); break;
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default: break;
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}
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for (int j = 0; j < carts.size(); j++) {
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if (j != i && carts[j].pos == carts[i].pos) {
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crashed.push_back(i);
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crashed.push_back(j);
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}
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}
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}
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return crashed;
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}
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};
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int main(int argc, char* argv[]) {
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std::string input = "../input/day_13_input";
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if (argc > 1) {
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input = argv[1];
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}
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std::ifstream file(input);
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std::string line;
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Map map;
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while (std::getline(file, line)) {
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map.grid.push_back(line);
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}
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Point pos;
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for (pos.y = 0; pos.y < map.grid.size(); pos.y++) {
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for (pos.x = 0; pos.x < map.grid[pos.y].size(); pos.x++) {
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switch (map.grid[pos.y][pos.x]) {
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case '^':
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map.carts.push_back(Cart{ pos, North, -1 });
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map.grid[pos.y][pos.x] = '|';
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break;
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case '>':
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map.carts.push_back(Cart{ pos, East, -1 }); break;
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map.grid[pos.y][pos.x] = '-';
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break;
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case 'v':
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map.carts.push_back(Cart{ pos, South, -1 }); break;
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map.grid[pos.y][pos.x] = '|';
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break;
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case '<':
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map.carts.push_back(Cart{ pos, West, -1 }); break;
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map.grid[pos.y][pos.x] = '-';
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break;
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default:
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break;
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}
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}
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}
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while (map.carts.size() > 1) {
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auto crashed = map.tick();
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std::sort(std::begin(crashed), std::end(crashed), std::greater<>());
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for (const auto index : crashed) {
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map.carts.erase(std::begin(map.carts) + index);
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}
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}
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printf("%d,%d\n", map.carts[0].pos.x, map.carts[0].pos.y);
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return 0;
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}

‎2018/sample_input/day_13_sample_input

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/->-\
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| | /----\
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| /-+--+-\ |
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| | | | v |
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\-+-/ \-+--/
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\------/
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/>-<\
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| |
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| /<+-\
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| | | v
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\>+</ |
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| ^
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\<->/

‎README.md

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@@ -9,4 +9,4 @@ This repository contains solutions to the Advent of Code puzzles.
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|2021 |1-25 | - | [Link](/2021/) |[Link](/2021/README.md) |
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|2020 |1-25 |1-25 | [Link](/2020/) |[Link](/2020/README.md) |
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|2019 |1-25 |1-7 | [Link](/2019/) |[Link](/2019/README.md) |
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|2018 |1-12 | | [Link](/2018/) |[Link](/2018/README.md) |
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|2018 |1-13 | | [Link](/2018/) |[Link](/2018/README.md) |

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