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Move c++ solutions into separate directory

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SebastianStork 2025-01-06 17:12:41 +01:00
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2024/day-06/main.cpp
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#include <iostream>
#include <set>
#include <vector>
using namespace std;
void readInput(vector<string> &mappedArea, pair<int, int> &startingPosition)
{
string line;
for (size_t rowIndex = 0; getline(cin, line); rowIndex++) {
for (size_t colIndex = 0; colIndex < line.size(); colIndex++) {
if (line[colIndex] == '^') {
startingPosition = {rowIndex, colIndex};
}
}
mappedArea.push_back(line);
}
}
bool isOutOfBounds(const vector<string> &mappedArea, const pair<int, int> &position)
{
return (position.first < 0 || position.first >= mappedArea.size())
|| (position.second < 0 || position.second >= mappedArea[0].size());
}
bool isObstacle(const vector<string> &mappedArea, const pair<int, int> &position)
{
char cell = mappedArea[position.first][position.second];
return cell == '#' || cell == 'O';
}
enum Direction { UP = 0, RIGHT, DOWN, LEFT };
bool takeStep(vector<string> &mappedArea,
pair<int, int> &currentPosition,
Direction &currentDirection,
set<pair<int, int>> *distinctPositions = nullptr)
{
const vector<pair<int, int>> directions = {{-1, 0}, {0, 1}, {1, 0}, {0, -1}};
pair<int, int> nextPosition = {currentPosition.first + directions[currentDirection].first,
currentPosition.second + directions[currentDirection].second};
if (isOutOfBounds(mappedArea, nextPosition)) {
return false;
}
if (isObstacle(mappedArea, nextPosition)) {
currentDirection = static_cast<Direction>((currentDirection + 1) % 4);
return true;
}
if (distinctPositions && mappedArea[nextPosition.first][nextPosition.second] != 'X') {
distinctPositions->insert({nextPosition.first, nextPosition.second});
}
mappedArea[currentPosition.first][currentPosition.second] = 'X';
mappedArea[nextPosition.first][nextPosition.second] = '^';
currentPosition = nextPosition;
return true;
}
bool isLoopCausingObstruction(const pair<int, int> &obstructionPosition,
vector<string> mappedArea,
pair<int, int> currentPosition,
Direction currentDirection)
{
if (obstructionPosition == currentPosition) {
return false;
}
mappedArea[obstructionPosition.first][obstructionPosition.second] = 'O';
set<tuple<int, int, Direction>> states;
states.insert({currentPosition.first, currentPosition.second, currentDirection});
while (takeStep(mappedArea, currentPosition, currentDirection)) {
tuple<int, int, Direction> currentState = {currentPosition.first,
currentPosition.second,
currentDirection};
if (states.count(currentState)) {
return true;
}
states.insert(currentState);
}
return false;
}
int main()
{
vector<string> mappedArea;
pair<int, int> startingPosition;
Direction startingDirection = UP;
readInput(mappedArea, startingPosition);
pair<int, int> currentPosition = startingPosition;
Direction currentDirection = startingDirection;
set<pair<int, int>> distinctPositions = {currentPosition};
while (takeStep(mappedArea, currentPosition, currentDirection, &distinctPositions))
;
int numberOfDistinctPositions = distinctPositions.size();
int numberOfLoopCausingObstructions = 0;
for (const pair<int, int> &obstructionPosition : distinctPositions) {
numberOfLoopCausingObstructions += isLoopCausingObstruction(obstructionPosition,
mappedArea,
startingPosition,
startingDirection);
}
// Part one
cout << "Number of distinct positions visited before leaving: " << numberOfDistinctPositions
<< endl;
// Part two
cout << "Number of potential obstructions to create a loop: " << numberOfLoopCausingObstructions
<< endl;
}