144 lines
3.5 KiB
C++
144 lines
3.5 KiB
C++
#include <bits/stdc++.h>
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using namespace std;
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// ifstream in("test.in");
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// ofstream out("test.out");
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struct Domino {
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int side1;
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int side2;
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};
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// Global variables
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int n;
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int max_length = 1;
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unordered_set<Domino*> used_dominos;
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vector<Domino*> dominos_by_side[7];
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// Recursive solution
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void buildTrain(int next_side, int current_length) {
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// cout << "Building train; Current length: " << current_length << "; next side: " << next_side << endl;
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if (current_length > max_length) {
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max_length = current_length;
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// Debug print
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// cout << "updated to " << current_length << endl;
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// if (max_length == 8) {
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// cout << "found 8" << endl;
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// for (auto it = used_dominos.begin(); it != used_dominos.end(); it++) {
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// cout << (*it)->side1 << " " << (*it)->side2 << endl;
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// }
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// }
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}
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int stop = dominos_by_side[next_side].size();
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for (int i = 0; i < stop; i++) {
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// Looking at Domino dominos_by_side[next_side][i]
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#define matched_domino dominos_by_side[next_side][i]
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// Skip if already part of the train
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if (used_dominos.count(matched_domino) > 0) {
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continue;
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}
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// The logic for elongating the train
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used_dominos.insert(matched_domino);
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// Figure out if the domino matched by side1 or side2:
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int other_side;
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if ((matched_domino->side1) == next_side) {
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other_side = matched_domino->side2;
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} else {
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other_side = matched_domino->side1;
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}
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// The recursion
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buildTrain(other_side, current_length + 1);
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// Deconstruct
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used_dominos.erase(matched_domino);
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}
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}
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int main(int argc, char *argv[]) {
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string inName = "test.in";
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string outName = "test.out";
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if (argc > 1) {
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inName = argv[1];
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cout << "Using \"" << inName << "\" for test name" << endl;
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} else {
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cout << "Warning: no in name provided, defaulting to test.in" << endl;
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}
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if (argc > 2) {
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outName = argv[2];
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cout << "Using \"" << outName << "\" for out name" << endl;
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} else {
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cout << "Warning: no out name proviced, defaulting to test.out" << endl;
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}
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ifstream in(inName);
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ofstream out(outName);
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in >> n;
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// cout << "n: " << n << endl;
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if (n < 2) {
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out << "1";
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in.close();
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out.close();
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return 0;
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}
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Domino* dominos[n];
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for (int i = 0; i < n; i++) {
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Domino* domino = new Domino();
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in >> (*domino).side1;
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in >> (*domino).side2;
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dominos[i] = domino;
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dominos_by_side[(domino -> side1)].push_back(domino);
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dominos_by_side[(domino -> side2)].push_back(domino);
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}
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// Debug print
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for (int j = 0; j < n; j++) {
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cout << dominos[j] << endl;
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cout << (dominos[j]->side1) << " " << (dominos[j]->side2) << endl;
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}
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used_dominos.clear();
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// for (int i = 0; i < n; i++) {
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// #define start_domino dominos[i]
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// // cout << "starting with domino " << start_domino->side1 << " " << start_domino->side2 << "" << start_domino << endl;
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// used_dominos.insert(start_domino);
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// buildTrain(start_domino->side1, 1);
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// buildTrain(start_domino->side2, 1);
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// used_dominos.clear();
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// }
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used_dominos.insert(dominos[2]);
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cout << "start " << dominos[2]->side1 << " " << dominos[2]->side2 << endl;
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buildTrain(dominos[2]->side1, 1);
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cout << "Result: " << max_length << endl;
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return 0;
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}
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