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Advent2021/Day 13/part1.cpp.cpp

79 lines
1.9 KiB
C++

#include <iostream>
#include <string>
#include <vector>
#include <set>
#include <utility>
using namespace std;
set<pair<int,int>> flip_about(set<pair<int,int>> input_points, bool x_flip, int value);
int main(int argc, char* argv[])
{
string line;
bool coord_input = true;
set<pair<int,int>> coords;
vector<pair<bool,int>> folds;
while(getline(cin, line))
{
if (0 == line.size())
{
coord_input = false;
continue;
}
if (coord_input)
{
string::size_type n = line.find(',');
pair<int,int> coord(stoi(line.substr(0,n)), stoi(line.substr(n+1)));
coords.insert(coord);
}
else
{
string::size_type n = line.find_last_of(' ');
line = line.substr(n+1);
pair<bool,int> fold(line[0]=='x', stoi(line.substr(2)));
folds.push_back(fold);
}
}
coords = flip_about(coords, folds[0].first, folds[0].second);
cout << coords.size() << endl;
}
set<pair<int,int>> flip_about(set<pair<int,int>> input_points, bool x_flip, int value)
{
set<pair<int,int>> output_points;
set<pair<int,int>>::iterator it = input_points.begin();
for(; it != input_points.end(); ++it)
{
if (x_flip)
{
if (it->first > value)
{
pair<int,int> flipped_coord(2*value-it->first, it->second);
output_points.insert(flipped_coord);
}
else
{
output_points.insert(*it);
}
}
else
{
if (it->second > value)
{
pair<int,int> flipped_coord(it->first, 2*value-it->second);
output_points.insert(flipped_coord);
}
else
{
output_points.insert(*it);
}
}
}
return output_points;
}