2022/city/10/domino solution
This commit is contained in:
209
2022/city/10/domino/main.cpp
Normal file
209
2022/city/10/domino/main.cpp
Normal file
@@ -0,0 +1,209 @@
|
||||
#include <bits/stdc++.h>
|
||||
|
||||
using namespace std;
|
||||
|
||||
// ifstream in("test.in");
|
||||
// ofstream out("test.out");
|
||||
|
||||
|
||||
|
||||
struct Domino {
|
||||
int side1;
|
||||
int side2;
|
||||
};
|
||||
|
||||
|
||||
// Global variables
|
||||
int n;
|
||||
int max_length = 1;
|
||||
Domino* dominos[28];
|
||||
vector<Domino*> dominos_by_side[7];
|
||||
unordered_set<Domino*> ignored_dominos;
|
||||
|
||||
|
||||
bool evaluate(unordered_set<Domino*>& ignore_candidates) {
|
||||
ignore_candidates.clear();
|
||||
|
||||
// Filled during the loop, used later
|
||||
unordered_set<Domino*> used_dominos;
|
||||
|
||||
// Find degree of each pip
|
||||
int odd_vertices_count = 0;
|
||||
for (int i = 0; i < 7; i++) {
|
||||
int dominos_count = 0;
|
||||
for (auto it = dominos_by_side[i].begin(); it != dominos_by_side[i].end(); it++) {
|
||||
if (ignored_dominos.count(*it) != 1) {
|
||||
dominos_count++;
|
||||
used_dominos.insert(*it);
|
||||
}
|
||||
}
|
||||
|
||||
// Mark as ignored candidate all dominos with pips that have odd degree
|
||||
if (dominos_count % 2 == 1) {
|
||||
odd_vertices_count++;
|
||||
ignore_candidates.insert(dominos_by_side[i].begin(), dominos_by_side[i].end());
|
||||
}
|
||||
}
|
||||
// cout << odd_vertices_count << " odd vertices found" << endl;
|
||||
|
||||
// Condition 1
|
||||
if (odd_vertices_count > 2) {
|
||||
return false;
|
||||
}
|
||||
|
||||
// Now evaluate using DFS here
|
||||
// cout << "Evaluating with DFS" << endl;
|
||||
unordered_set<Domino*> visited_dominos;
|
||||
visited_dominos.clear();
|
||||
deque<Domino*> domino_queue;
|
||||
domino_queue.push_back(*used_dominos.begin());
|
||||
visited_dominos.insert(*used_dominos.begin());
|
||||
bool visited_pips[7];
|
||||
for (int i = 0; i < 7; i++) {
|
||||
visited_pips[i] = 0;
|
||||
}
|
||||
|
||||
while (domino_queue.size() > 0) {
|
||||
Domino* domino = domino_queue.front();
|
||||
domino_queue.pop_front();
|
||||
|
||||
if (!visited_pips[domino->side1]) {
|
||||
for (auto it = dominos_by_side[domino->side1].begin(); it != dominos_by_side[domino->side1].end(); it++) {
|
||||
if (ignored_dominos.count(*it) == 1) {
|
||||
continue;
|
||||
}
|
||||
if (visited_dominos.count(*it) == 0) {
|
||||
visited_dominos.insert(*it);
|
||||
domino_queue.push_back(*it);
|
||||
}
|
||||
}
|
||||
visited_pips[domino->side1] = 1;
|
||||
}
|
||||
|
||||
if (!visited_pips[domino->side2]) {
|
||||
for (auto it = dominos_by_side[domino->side2].begin(); it != dominos_by_side[domino->side2].end(); it++) {
|
||||
if (ignored_dominos.count(*it) == 1) {
|
||||
continue;
|
||||
}
|
||||
if (visited_dominos.count(*it) == 0) {
|
||||
visited_dominos.insert(*it);
|
||||
domino_queue.push_back(*it);
|
||||
}
|
||||
}
|
||||
visited_pips[domino->side2] = 1;
|
||||
}
|
||||
}
|
||||
|
||||
if (visited_dominos.size() != used_dominos.size()) {
|
||||
cout << "DFS invalid " << visited_dominos.size() << "/" << used_dominos.size() << " visited" << endl;
|
||||
// ignore_candidates.insert(used_dominos.begin(), used_dominos.end());
|
||||
if (visited_dominos.size() > (used_dominos.size() / 2)) {
|
||||
for (auto it = used_dominos.begin(); it != used_dominos.end(); it++) {
|
||||
if (visited_dominos.count(*it) == 0) {
|
||||
ignore_candidates.insert(*it);
|
||||
}
|
||||
}
|
||||
} else {
|
||||
ignore_candidates.insert(used_dominos.begin(), used_dominos.end());
|
||||
}
|
||||
return false;
|
||||
}
|
||||
// cout << "DFS VALID" << endl;
|
||||
return true;
|
||||
}
|
||||
|
||||
|
||||
bool evaluate() {
|
||||
unordered_set<Domino*> empty_set;
|
||||
return evaluate(empty_set);
|
||||
}
|
||||
|
||||
|
||||
|
||||
|
||||
void solve() {
|
||||
// cout << ignored_dominos.size() << " ignored dominos deep" << endl;
|
||||
|
||||
unordered_set<Domino*> ignore_candidates; // populated in evaluate()
|
||||
if (evaluate(ignore_candidates)) {
|
||||
cout << "Found new max length " << max_length << endl;
|
||||
max_length = max(max_length, (int)(n - ignored_dominos.size()));
|
||||
return;
|
||||
}
|
||||
|
||||
// Evaluate if it's worth going deeper based on previous findings
|
||||
if (max_length > (n - ignored_dominos.size() - 1)) {
|
||||
return;
|
||||
}
|
||||
|
||||
// for (int i = 0; i < dominos_to_ignore.size(); i++) {
|
||||
for (auto it = ignore_candidates.begin(); it != ignore_candidates.end(); it++) {
|
||||
#define target_domino (*it)
|
||||
if (ignored_dominos.count(target_domino)) {
|
||||
continue;
|
||||
}
|
||||
ignored_dominos.insert(target_domino);
|
||||
|
||||
solve();
|
||||
|
||||
ignored_dominos.erase(target_domino);
|
||||
}
|
||||
}
|
||||
|
||||
|
||||
|
||||
// pips = vertices; dominos = edges
|
||||
// Solve Euler path
|
||||
int main(int argc, char *argv[]) {
|
||||
string inName = "test.in";
|
||||
string outName = "test.out";
|
||||
|
||||
if (argc > 1) {
|
||||
inName = argv[1];
|
||||
cout << "Using \"" << inName << "\" for test name" << endl;
|
||||
} else {
|
||||
cout << "Warning: no in name provided, defaulting to test.in" << endl;
|
||||
}
|
||||
|
||||
if (argc > 2) {
|
||||
outName = argv[2];
|
||||
cout << "Using \"" << outName << "\" for out name" << endl;
|
||||
} else {
|
||||
cout << "Warning: no out name proviced, defaulting to test.out" << endl;
|
||||
}
|
||||
|
||||
ifstream in(inName);
|
||||
ofstream out(outName);
|
||||
|
||||
in >> n;
|
||||
|
||||
// cout << "n: " << n << endl;
|
||||
|
||||
if (n < 2) {
|
||||
out << "1";
|
||||
in.close();
|
||||
out.close();
|
||||
return 0;
|
||||
}
|
||||
|
||||
for (int i = 0; i < n; i++) {
|
||||
Domino* domino = new Domino();
|
||||
in >> (*domino).side1;
|
||||
in >> (*domino).side2;
|
||||
|
||||
dominos[i] = domino;
|
||||
|
||||
dominos_by_side[(domino -> side1)].push_back(domino);
|
||||
dominos_by_side[(domino -> side2)].push_back(domino);
|
||||
}
|
||||
|
||||
ignored_dominos.clear();
|
||||
|
||||
solve();
|
||||
// ignored_dominos.insert(dominos[0]);
|
||||
// cout << dominos[0]->side1 << " " << dominos[0]->side2 << endl;
|
||||
cout << "Result: " << max_length << endl;
|
||||
|
||||
out << max_length << endl;
|
||||
return 0;
|
||||
}
|
||||
143
2022/city/10/domino/main_slow.cpp
Normal file
143
2022/city/10/domino/main_slow.cpp
Normal file
@@ -0,0 +1,143 @@
|
||||
#include <bits/stdc++.h>
|
||||
|
||||
using namespace std;
|
||||
|
||||
// ifstream in("test.in");
|
||||
// ofstream out("test.out");
|
||||
|
||||
|
||||
struct Domino {
|
||||
int side1;
|
||||
int side2;
|
||||
};
|
||||
|
||||
|
||||
// Global variables
|
||||
int n;
|
||||
int max_length = 1;
|
||||
unordered_set<Domino*> used_dominos;
|
||||
vector<Domino*> dominos_by_side[7];
|
||||
|
||||
|
||||
// Recursive solution
|
||||
void buildTrain(int next_side, int current_length) {
|
||||
// cout << "Building train; Current length: " << current_length << "; next side: " << next_side << endl;
|
||||
if (current_length > max_length) {
|
||||
max_length = current_length;
|
||||
|
||||
// Debug print
|
||||
// cout << "updated to " << current_length << endl;
|
||||
// if (max_length == 8) {
|
||||
// cout << "found 8" << endl;
|
||||
// for (auto it = used_dominos.begin(); it != used_dominos.end(); it++) {
|
||||
// cout << (*it)->side1 << " " << (*it)->side2 << endl;
|
||||
// }
|
||||
// }
|
||||
}
|
||||
|
||||
int stop = dominos_by_side[next_side].size();
|
||||
|
||||
for (int i = 0; i < stop; i++) {
|
||||
// Looking at Domino dominos_by_side[next_side][i]
|
||||
#define matched_domino dominos_by_side[next_side][i]
|
||||
// Skip if already part of the train
|
||||
if (used_dominos.count(matched_domino) > 0) {
|
||||
continue;
|
||||
}
|
||||
|
||||
|
||||
// The logic for elongating the train
|
||||
used_dominos.insert(matched_domino);
|
||||
|
||||
// Figure out if the domino matched by side1 or side2:
|
||||
int other_side;
|
||||
if ((matched_domino->side1) == next_side) {
|
||||
other_side = matched_domino->side2;
|
||||
} else {
|
||||
other_side = matched_domino->side1;
|
||||
}
|
||||
|
||||
// The recursion
|
||||
buildTrain(other_side, current_length + 1);
|
||||
|
||||
|
||||
// Deconstruct
|
||||
used_dominos.erase(matched_domino);
|
||||
}
|
||||
}
|
||||
|
||||
|
||||
int main(int argc, char *argv[]) {
|
||||
|
||||
string inName = "test.in";
|
||||
string outName = "test.out";
|
||||
|
||||
if (argc > 1) {
|
||||
inName = argv[1];
|
||||
cout << "Using \"" << inName << "\" for test name" << endl;
|
||||
} else {
|
||||
cout << "Warning: no in name provided, defaulting to test.in" << endl;
|
||||
}
|
||||
|
||||
if (argc > 2) {
|
||||
outName = argv[2];
|
||||
cout << "Using \"" << outName << "\" for out name" << endl;
|
||||
} else {
|
||||
cout << "Warning: no out name proviced, defaulting to test.out" << endl;
|
||||
}
|
||||
|
||||
ifstream in(inName);
|
||||
ofstream out(outName);
|
||||
|
||||
in >> n;
|
||||
|
||||
// cout << "n: " << n << endl;
|
||||
|
||||
if (n < 2) {
|
||||
out << "1";
|
||||
in.close();
|
||||
out.close();
|
||||
return 0;
|
||||
}
|
||||
|
||||
|
||||
Domino* dominos[n];
|
||||
for (int i = 0; i < n; i++) {
|
||||
Domino* domino = new Domino();
|
||||
in >> (*domino).side1;
|
||||
in >> (*domino).side2;
|
||||
|
||||
dominos[i] = domino;
|
||||
|
||||
dominos_by_side[(domino -> side1)].push_back(domino);
|
||||
dominos_by_side[(domino -> side2)].push_back(domino);
|
||||
}
|
||||
|
||||
// Debug print
|
||||
for (int j = 0; j < n; j++) {
|
||||
cout << dominos[j] << endl;
|
||||
cout << (dominos[j]->side1) << " " << (dominos[j]->side2) << endl;
|
||||
}
|
||||
|
||||
used_dominos.clear();
|
||||
// for (int i = 0; i < n; i++) {
|
||||
// #define start_domino dominos[i]
|
||||
|
||||
// // cout << "starting with domino " << start_domino->side1 << " " << start_domino->side2 << "" << start_domino << endl;
|
||||
// used_dominos.insert(start_domino);
|
||||
|
||||
// buildTrain(start_domino->side1, 1);
|
||||
// buildTrain(start_domino->side2, 1);
|
||||
|
||||
// used_dominos.clear();
|
||||
// }
|
||||
|
||||
used_dominos.insert(dominos[2]);
|
||||
cout << "start " << dominos[2]->side1 << " " << dominos[2]->side2 << endl;
|
||||
buildTrain(dominos[2]->side1, 1);
|
||||
|
||||
|
||||
cout << "Result: " << max_length << endl;
|
||||
|
||||
return 0;
|
||||
}
|
||||
Reference in New Issue
Block a user