112 lines
3.3 KiB
C++
112 lines
3.3 KiB
C++
#include <fstream>
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#include <iostream>
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#include <sstream>
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#include <vector>
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std::vector<std::vector<bool>> getMap( std::ifstream &file ) {
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std::vector<std::vector<bool>> ret{};
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std::vector<std::vector<std::pair<int,int>>> rocks{};
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int max_y = 0;
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std::string str;
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char tmp_c;
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while ( std::getline( file, str ) ) {
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rocks.emplace_back();
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int x = 0;
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int y = 0;
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std::stringstream ss( str );
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while(ss >> x) {
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ss >> tmp_c;
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ss >> y;
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if(y > max_y) {
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max_y = y;
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}
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rocks.back().push_back({x,y});
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ss >> tmp_c;
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ss >> tmp_c;
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}
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}
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// std::cout << "Resizing: " << max_y << std::endl;
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ret.resize(max_y+1);
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for(int i = 0; i <= max_y; i++) {
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ret[i].resize(1000, false);
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}
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for(auto &rock_line : rocks) {
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for(size_t i = 0; i < rock_line.size() - 1; i++) {
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// std::cout << "i: " << i << std::endl;
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// std::cout << "X: " << rock_line[i].first << "->" << rock_line[i+1].first << std::endl;
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// std::cout << "Y: " << rock_line[i].second << "->" << rock_line[i+1].second << std::endl;
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int x_diff = rock_line[i+1].first - rock_line[i].first;
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x_diff /= abs(x_diff);
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int y_diff = rock_line[i+1].second - rock_line[i].second;
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y_diff /= abs(y_diff);
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int x = rock_line[i].first;
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int y = rock_line[i].second;
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while(x != rock_line[i+1].first || y != rock_line[i+1].second) {
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// std::cout << "X: " << x << ", Y: " << y << std::endl;
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ret[y][x] = true;
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x += x_diff;
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y += y_diff;
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}
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ret[y][x] = true;
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}
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}
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return ret;
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}
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bool willRest(std::vector<std::vector<bool>> &map, size_t x_source, size_t y_source) {
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size_t x = x_source;
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size_t y = y_source;
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while(y < map.size() - 1) {
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// std::cout << "CHECKING " << "{" << x << ", " << y << "}" << std::endl;
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if(!map[y+1][x]) {
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y++;
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} else if(!map[y+1][x-1]) {
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y++;
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x--;
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} else if(!map[y+1][x+1]) {
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y++;
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x++;
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} else {
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map[y][x] = true;
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if(x == x_source && y == y_source) {
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return false;
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}
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// std::cout << "TRUE" << std::endl;
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return true;
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}
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}
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return false;
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}
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size_t part1(const std::vector<std::vector<bool>> &map_in) {
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auto map = map_in;
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size_t result = 0;
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while(willRest(map, 500, 0)) {
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result++;
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}
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return result;
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}
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size_t part2(const std::vector<std::vector<bool>> &map_in) {
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auto map = map_in;
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map.resize(map.size()+2);
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map[map.size()-2].resize(1000, false);
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map.back().resize(1000, true);
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size_t result = 0;
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while(willRest(map, 500, 0)) {
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result++;
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}
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result++; // the source position sand
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return result;
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}
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int main() {
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std::ifstream input_file( "input" );
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auto map = getMap( input_file );
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std::cout << "There will be \033[91;1m" << part1(map)
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<< "\033[0m grains of sand before it starts falling into the abyss." << std::endl;
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std::cout << "There will be \033[91;1m" << part2(map)
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<< "\033[0m grains of sand before it stabilizes." << std::endl;
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}
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