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#include <iostream>
#include <fstream>
#include <string>
#include <vector>
#include <algorithm>
#include "../utils.h"
int xytoi (int size, int x, int y) { return size*y + x; }
int itox (int size, int i) { return i % size; }
int itoy (int size, int i) { return i / size; }
bool oob (int sizex, int sizey, int x, int y) {
if (x < 0 || y < 0) return true;
if (x >= sizex || y >= sizey) return true;
return false;
}
std::vector<std::pair<int, int>> get_dirs() {
std::vector<std::pair<int, int>> dirs {
{ 1, 0 }, { 0, 1 }, { -1, 0 }, { 0, -1 }
};
return dirs;
}
bool is_min (std::vector<int> grid, int size, int i) {
int x = itox(size, i);
int y = itoy(size, i);
for (auto dir : get_dirs()) {
int j = xytoi(size, dir.first+x, dir.second+y);
if (!oob(size, grid.size()/size, dir.first+x, dir.second+y))
if (grid[j] <= grid[i])
return false;
}
return true;
}
std::vector<int> flood (std::vector<int> grid, int size, int i) {
std::vector<int> visit ;
std::vector<int> q { i };
while (q.size() > 0) {
int x = itox(size, q[0]);
int y = itoy(size, q[0]);
if (std::find(std::begin(visit), std::end(visit), q[0]) == std::end(visit))
visit.push_back(q[0]);
q.erase(std::begin(q));
for (auto dir : get_dirs()) {
int j = xytoi(size, dir.first+x, dir.second+y);
if (std::find(std::begin(visit), std::end(visit), j) != std::end(visit))
continue;
if (!oob(size, grid.size()/size, dir.first+x, dir.second+y)) {
if (grid[j] < 9) {
q.push_back(j);
}
}
}
}
return visit;
}
int main (int argc, char * argv[]) {
std::string raw;
std::getline(std::ifstream(argv[1]), raw, '\0');
std::vector<std::string> lines;
split(lines, raw, "\n");
int size = 0;
std::vector<int> grid;
for (std::string line : lines) {
if (line.size() == 0) continue;
size = 0;
for (char c : line) {
grid.push_back(std::stoi(std::string { c } ));
size++;
}
}
std::cout << "lowpoints: ";
std::vector<int> lows;
int sum = 0;
for (std::size_t i=0; i<grid.size(); i++) {
if (is_min(grid, size, i)) {
std::cout << "(" << itox(size, i) << " " << itoy(size, i) << "), ";
sum += grid[i]+1;
lows.push_back(i);
}
}
std::cout << std::endl;
std::cout << "sum of risk: " << sum << std::endl;
std::vector<int> isles;
for (auto low : lows) {
auto visit = flood(grid, size, low);
isles.push_back(visit.size());
}
std::sort(std::begin(isles), std::end(isles), std::greater<int>());
int res = isles[0] * isles[1] * isles[2];
std::cout << "three largest basins multiplied: " << res << std::endl;
return 0;
}
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