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#include "aoc.h"
#include <deque>
#include <map>
namespace aoc2016 {
void bfs(maze::pos p, maze& m, std::map<maze::pos, int>& ds) {
ds.insert({p, 0});
std::deque<maze::pos> q;
q.push_back(p);
while (!q.empty()) {
auto s = q.size();
while (s-- > 0) {
maze::pos p0 = q.front();
q.pop_front();
maze::pos ns[4] = {
{p0.x - 1, p0.y},
{p0.x + 1, p0.y},
{p0.x, p0.y - 1},
{p0.x, p0.y + 1},
};
auto& d = ds[p0];
for (auto& n : ns) {
if (m.get(n.x, n.y) != '#') {
auto px = ds.insert({n, d + 1});
if (px.second) {
q.push_back(n);
}
if (!px.second && px.first->second > d + 1) {
px.first->second = d + 1;
q.push_back(n);
}
}
}
}
}
auto& ns = m.numbers;
for (auto it = ds.begin(); it != ds.end();) {
if (ns.find(it->first) == ns.end()) {
it = ds.erase(it);
} else {
it++;
}
}
}
int to0(int i, maze& mz, const std::vector<std::map<maze::pos, int>>& vds) {
auto& m = vds[i];
for (auto& kv : m) {
if (mz.get(kv.first.x, kv.first.y) == '0') {
return kv.second;
}
}
return INT32_MAX;
}
struct mdistance {
int d0 = INT32_MAX;
int d1 = INT32_MAX;
};
void shortest_route(int i, int total, std::set<int> selected, size_t max, maze& mz,
const std::vector<std::map<maze::pos, int>>& vds, mdistance* shortest) {
selected.insert(i);
if (selected.size() == max) {
if (shortest->d0 > total) {
shortest->d0 = total;
}
int t0 = to0(i, mz, vds);
if (shortest->d1 > total + t0) {
shortest->d1 = total + t0;
}
} else {
for (auto& kv : vds[i]) {
int n = mz.get(kv.first.x, kv.first.y) - '0';
if (selected.find(n) == selected.end()) {
shortest_route(n, total + kv.second, selected, max, mz, vds, shortest);
}
}
}
}
std::pair<int64_t, int64_t> day24(line_view file) {
maze mz{179, 43}; // input
// maze mz{11, 5}; // demo
int r{0};
per_line(file, [&r, &mz](line_view lv) {
mz.load(r++, lv);
return true;
});
std::vector<std::map<maze::pos, int>> vds;
constexpr int max = 8; // input
// constexpr int max = 5; // demo
vds.resize(max);
for (auto& n : mz.numbers) {
int i = mz.get(n.x, n.y) - '0';
auto& ds = vds[i];
bfs(n, mz, ds);
}
mdistance shortest[max];
for (size_t i = 0; i < vds.size(); i++) {
std::set<int> selected;
shortest_route(i, 0, selected, max, mz, vds, &shortest[i]);
}
// for (auto s : shortest) {
// printf("%d %d\n", s.d0, s.d1);
// }
// for (auto& ds : vds) {
// for (auto& kv : ds) {
// printf("(%c: %d) ", mz.get(kv.first.x, kv.first.y), kv.second);
// }
// printf("\n");
// }
// mz.print();
// for (auto& p : mz.numbers) {
// printf("%c: (%d, %d)\n", mz.get(p.x, p.y), p.x, p.y);
// }
return {shortest[0].d0, shortest[0].d1};
}
} // namespace aoc2016
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