Submission #840578

#	Submission time	Handle	Problem	Language	Result	Execution time	Memory
840578	2023-08-31T14:05:28 Z	happypotato	Longest Trip (IOI23_longesttrip)	C++17	70 / 100	26 ms	720 KB

longesttrip

#include "longesttrip.h"

#include <bits/stdc++.h>
#pragma GCC optimize("O2")
using namespace std;
// #define int long long // remove when necessary
#define pii pair<int, int>
#define ff first
#define ss second
#define pb push_back
#define ll long long
const int mxN = 256;
vector<int> adj[mxN];
vector<int> grp[mxN];
int conn[mxN][mxN];
int callcnt;
bool con(int x, int y) {
	// cerr << "CALLx " << x << ' ' << y << endl;
	if (x == y) return (conn[x][x] = 1);
	if (conn[x][y] != -1) return conn[x][y];
	callcnt++;
	return (conn[x][y] = conn[y][x] = are_connected({x}, {y}));
}
bool Con(vector<int> x, vector<int> y) {
	if (x.size() == 1 && y.size() == 1) {
		return con(x[0], y[0]);
	}
	// cerr << "CALL\n";
	// for (int &cur : x) cerr << cur << ' ';
	// cerr << endl;
	// for (int &cur : y) cerr << cur << ' ';
	// cerr << endl;
	callcnt++;
	return are_connected(x, y);
}
int n;
int dsupp[mxN];
vector<int> nxt[mxN];
bool vis[mxN];
void resetvis() {
	for (int i = 0; i < n; i++) vis[i] = false;
}
void reset() {
	callcnt = 0;
	for (int i = 0; i < n; i++) {
		adj[i].clear();
		grp[i].clear();
		for (int j = 0; j < n; j++) {
			conn[i][j] = -1;
		}
		dsupp[i] = i;
		nxt[i].clear();
		vis[i] = false;
	}
}
int DSUFind(int u) {
	if (dsupp[u] == u) return u;
	return (dsupp[u] = DSUFind(dsupp[u]));
}
void DSUMerge(int u, int v) {
	u = DSUFind(u); v = DSUFind(v);
	if (u != v) dsupp[v] = u;
}
vector<int> GetPath(int st) {
	resetvis();
	vector<int> res;
	while (true) {
		res.pb(st);
		vis[st] = true;
		bool found = false;
		for (int &v : nxt[st]) {
			if (!vis[v]) {
				st = v;
				found = true;
				break;
			}
		}
		if (!found) break;
	}
	return res;
}
vector<int> MakePath(vector<int> &v) {
	if (v.size() == 1) return {v[0]};
	if (v.size() == 2) {
		if (con(v[0], v[1])) return {v[0], v[1]};
		else return {v[0]};
	}
	if (v.size() == 3) {
		if (con(v[0], v[1]) && con(v[0], v[2])) return {v[1], v[0], v[2]};
		if (con(v[0], v[1]) && con(v[1], v[2])) return {v[0], v[1], v[2]};
		if (con(v[0], v[2]) && con(v[1], v[2])) return {v[0], v[2], v[1]};
		if (con(v[0], v[1])) return {v[0], v[1]};
		if (con(v[0], v[2])) return {v[0], v[2]};
		if (con(v[1], v[2])) return {v[1], v[2]};
		return {v[0]};
	}
	for (int i = 0; i < n; i++) {
		nxt[i].clear();
	}
	pair<pii, pii> cur = {{v[0], v[0]}, {v[1], v[1]}};
	for (int i = 2; i < (int)(v.size()); i++) {
		if (con(cur.ff.ff, cur.ss.ff)) {
			nxt[cur.ff.ff].pb(cur.ss.ff);
			nxt[cur.ss.ff].pb(cur.ff.ff);
			cur.ff.ff = cur.ss.ss;
			cur.ss = {v[i], v[i]};
		} else if (con(cur.ff.ff, v[i])) {
			nxt[cur.ff.ff].pb(v[i]);
			nxt[v[i]].pb(cur.ff.ff);
			cur.ff.ff = v[i];
		} else {
			conn[cur.ss.ff][v[i]] = conn[v[i]][cur.ss.ff] = 1;
			nxt[cur.ss.ff].pb(v[i]);
			nxt[v[i]].pb(cur.ss.ff);
			cur.ss.ff = v[i];
		}
	}
	int st;
	if (con(cur.ff.ff, cur.ss.ff)) {
		nxt[cur.ff.ff].pb(cur.ss.ff);
		nxt[cur.ss.ff].pb(cur.ff.ff);
		st = cur.ff.ss;
	} else if (con(cur.ff.ff, cur.ss.ss)) {
		nxt[cur.ff.ff].pb(cur.ss.ss);
		nxt[cur.ss.ss].pb(cur.ff.ff);
		st = cur.ff.ss;
	} else if (con(cur.ff.ss, cur.ss.ff)) {
		nxt[cur.ff.ss].pb(cur.ss.ff);
		nxt[cur.ss.ff].pb(cur.ff.ss);
		st = cur.ff.ff;
	} else if (con(cur.ff.ss, cur.ss.ss)) {
		nxt[cur.ff.ss].pb(cur.ss.ss);
		nxt[cur.ss.ss].pb(cur.ff.ss);
		st = cur.ff.ff;
	} else {
		vector<int> res[2];
		res[0] = GetPath(cur.ff.ff);
		res[1] = GetPath(cur.ss.ff);

		vector<int> take[2];
		take[0] = res[0];
		take[1] = res[1];

		// cerr << "res0: ";
		// for (int &x : res[0]) cerr << x << ' ';
		// cerr << endl;
		// cerr << "res1: ";
		// for (int &x : res[1]) cerr << x << ' ';
		// cerr << endl;

		set<int> s; for(auto i : take[0]) s.insert(i);
		for(auto i : take[1]) assert(!s.count(i));
		vector<int> split[2];
		while (take[0].size() >= 2) {
			split[0].clear();
			split[1].clear();
			int cut = (int)(take[0].size()) / 2;
			for (int i = 0; i < cut; i++) split[0].pb(take[0][i]);
			for (int i = cut; i < (int)(take[0].size()); i++) split[1].pb(take[0][i]);
			if (Con(split[0], take[1])) take[0] = split[0];
			else take[0] = split[1];
		}
		while (take[1].size() >= 2) {
			split[0].clear();
			split[1].clear();
			int cut = (int)(take[1].size()) / 2;
			for (int i = 0; i < cut; i++) split[0].pb(take[1][i]);
			for (int i = cut; i < (int)(take[1].size()); i++) split[1].pb(take[1][i]);
			if (Con(take[0], split[0])) take[1] = split[0];
			else take[1] = split[1];
		}

		bool found = false;
		for (int i = 0; i < (int)(res[0].size()); i++) {
			if (res[0][i] != take[0][0]) continue;
			for (int j = 0; j < (int)(res[1].size()); j++) {
				if (res[1][j] != take[1][0]) continue;
				if (true) {
					// cerr << "FOUND " << res[0][i] << ' ' << res[1][j] << endl;
					nxt[res[0][i]].pb(res[1][j]);
					nxt[res[1][j]].pb(res[0][i]);
 
					if (res[0].size() >= 3) {
						nxt[cur.ff.ff].pb(cur.ff.ss);
						nxt[cur.ff.ss].pb(cur.ff.ff);
						// cerr << "RES0 ";
						// for (int &x : res[0]) cerr << x << ' ';
						// cerr << endl;
						st = (i == 0 ? res[0].back() : res[0][i - 1]);
						// cerr << "ST " << st << endl;
						vector<int>::iterator it;
						for (it = nxt[st].begin(); it != nxt[st].end(); ++it) {
							if (*it == res[0][i]) {
								nxt[st].erase(it);
								break;
							}
						}
						for (it = nxt[res[0][i]].begin(); it != nxt[res[0][i]].end(); ++it) {
							if (*it == st) {
								nxt[res[0][i]].erase(it);
								break;
							}
						}
					} else {
						st = (res[0].size() == 2 ? res[0][i ^ 1] : res[0][i]);
					}
 
					if (res[1].size() >= 3) {
						nxt[cur.ss.ff].pb(cur.ss.ss);
						nxt[cur.ss.ss].pb(cur.ss.ff);
						int tar = (j == 0 ? res[1].back() : res[1][j + 1]);
						vector<int>::iterator it;
						for (it = nxt[tar].begin(); it != nxt[tar].end(); ++it) {
							if (*it == res[1][j]) {
								nxt[tar].erase(it);
								break;
							}
						}
						for (it = nxt[res[1][j]].begin(); it != nxt[res[1][j]].end(); ++it) {
							if (*it == tar) {
								nxt[res[1][j]].erase(it);
								break;
							}
						}
					}
 
					found = true;
					break;
				}
			}
			if (found) break;
		}

		// cerr << "END\n";
	}

	// cerr << "find path for: ";
	// for (int &x : v) cerr << x << ' ';
	// cerr << endl;
	
	vector<int> res = GetPath(st);

	// cerr << "st: " << st << endl;
	// cerr << "result: ";
	// for (int &x : res) cerr << x << ' ';
	// cerr << endl;

	return res;
}
vector<int> longest_trip(int N, int D)
{
	n = N;
	reset();

	queue<int> q;
	for (int i = 0; i < n; i++) {
		grp[i].clear();
		grp[i].pb(i);
		q.push(i);
	}
	while (q.size() >= 3) {
		int a = q.front(); q.pop();
		int b = q.front(); q.pop();
		int c = q.front(); q.pop();
		// cerr << a << ' ' << b << ' ' << c << endl;
		if (Con(grp[a], grp[b])) {
			DSUMerge(a, b);
			for (int &x : grp[b]) grp[a].pb(x);
			grp[b].clear();
			q.push(a);
			q.push(c);
		} else if (Con(grp[a], grp[c])) {
			DSUMerge(a, c);
			for (int &x : grp[c]) grp[a].pb(x);
			grp[c].clear();
			q.push(a);
			q.push(b);
		} else {
			DSUMerge(b, c);
			for (int &x : grp[c]) grp[b].pb(x);
			grp[c].clear();
			q.push(a);
			q.push(b);
		}
	}
	int fina = q.front(); q.pop();
	int finb = q.front(); q.pop();
	if (Con(grp[fina], grp[finb])) {
		DSUMerge(fina, finb);
		for (int &x : grp[finb]) grp[fina].pb(x);
		grp[finb].clear();
	}

	// cerr << "CALLCNT " << callcnt << endl;

	vector<int> best = {};
	for (int i = 0; i < n; i++) {
		if (grp[i].empty()) continue;
		vector<int> res = MakePath(grp[i]);
		if (res.size() > best.size()) {
			best = res;
		}
	}
	return best;
}

Compilation message

longesttrip.cpp: In function 'std::vector<int> MakePath(std::vector<int>&)':
longesttrip.cpp:241:30: warning: 'st' may be used uninitialized in this function [-Wmaybe-uninitialized]
  241 |  vector<int> res = GetPath(st);
      |                              ^

Subtask #0

0.0 / 0.0

#	Verdict	Execution time	Memory	Grader output
1	Correct	0 ms	208 KB	Output is correct
2	Correct	7 ms	644 KB	Output is correct

Subtask #1

5.0 / 5.0

#	Verdict	Execution time	Memory	Grader output
1	Correct	8 ms	208 KB	Output is correct
2	Correct	12 ms	208 KB	Output is correct
3	Correct	15 ms	336 KB	Output is correct
4	Correct	13 ms	464 KB	Output is correct
5	Correct	14 ms	592 KB	Output is correct

Subtask #2

10.0 / 10.0

#	Verdict	Execution time	Memory	Grader output
1	Correct	10 ms	208 KB	Output is correct
2	Correct	11 ms	208 KB	Output is correct
3	Correct	16 ms	464 KB	Output is correct
4	Correct	14 ms	464 KB	Output is correct
5	Correct	14 ms	592 KB	Output is correct
6	Correct	13 ms	256 KB	Output is correct
7	Correct	17 ms	388 KB	Output is correct
8	Correct	8 ms	336 KB	Output is correct
9	Correct	17 ms	336 KB	Output is correct
10	Correct	13 ms	592 KB	Output is correct
11	Correct	17 ms	640 KB	Output is correct
12	Correct	14 ms	592 KB	Output is correct
13	Correct	8 ms	596 KB	Output is correct

Subtask #3

25.0 / 25.0

#	Verdict	Execution time	Memory	Grader output
1	Correct	13 ms	208 KB	Output is correct
2	Correct	12 ms	388 KB	Output is correct
3	Correct	15 ms	336 KB	Output is correct
4	Correct	10 ms	468 KB	Output is correct
5	Correct	13 ms	592 KB	Output is correct
6	Correct	13 ms	208 KB	Output is correct
7	Correct	16 ms	208 KB	Output is correct
8	Correct	16 ms	336 KB	Output is correct
9	Correct	11 ms	388 KB	Output is correct
10	Correct	18 ms	640 KB	Output is correct
11	Correct	17 ms	592 KB	Output is correct
12	Correct	13 ms	592 KB	Output is correct
13	Correct	17 ms	592 KB	Output is correct
14	Correct	13 ms	208 KB	Output is correct
15	Correct	14 ms	364 KB	Output is correct
16	Correct	11 ms	336 KB	Output is correct
17	Correct	10 ms	336 KB	Output is correct
18	Correct	17 ms	336 KB	Output is correct
19	Correct	17 ms	336 KB	Output is correct
20	Correct	16 ms	448 KB	Output is correct
21	Correct	18 ms	592 KB	Output is correct
22	Correct	18 ms	592 KB	Output is correct
23	Correct	16 ms	592 KB	Output is correct
24	Correct	18 ms	592 KB	Output is correct
25	Correct	9 ms	208 KB	Output is correct
26	Correct	7 ms	208 KB	Output is correct
27	Correct	16 ms	208 KB	Output is correct
28	Correct	18 ms	388 KB	Output is correct
29	Correct	18 ms	208 KB	Output is correct
30	Correct	13 ms	336 KB	Output is correct
31	Correct	9 ms	388 KB	Output is correct
32	Correct	17 ms	400 KB	Output is correct
33	Correct	12 ms	336 KB	Output is correct
34	Correct	8 ms	336 KB	Output is correct
35	Correct	14 ms	336 KB	Output is correct
36	Correct	15 ms	608 KB	Output is correct
37	Correct	19 ms	600 KB	Output is correct
38	Correct	21 ms	584 KB	Output is correct
39	Correct	15 ms	672 KB	Output is correct
40	Correct	18 ms	616 KB	Output is correct
41	Correct	18 ms	592 KB	Output is correct
42	Correct	23 ms	592 KB	Output is correct
43	Correct	22 ms	620 KB	Output is correct
44	Correct	22 ms	588 KB	Output is correct
45	Correct	16 ms	208 KB	Output is correct
46	Correct	13 ms	208 KB	Output is correct
47	Correct	14 ms	336 KB	Output is correct
48	Correct	18 ms	336 KB	Output is correct
49	Correct	17 ms	336 KB	Output is correct
50	Correct	19 ms	400 KB	Output is correct
51	Correct	11 ms	392 KB	Output is correct
52	Correct	23 ms	576 KB	Output is correct
53	Correct	17 ms	444 KB	Output is correct
54	Correct	15 ms	508 KB	Output is correct
55	Correct	22 ms	432 KB	Output is correct
56	Correct	16 ms	616 KB	Output is correct
57	Correct	22 ms	612 KB	Output is correct
58	Correct	21 ms	644 KB	Output is correct
59	Correct	22 ms	628 KB	Output is correct
60	Correct	17 ms	720 KB	Output is correct
61	Correct	17 ms	644 KB	Output is correct
62	Correct	21 ms	592 KB	Output is correct
63	Correct	26 ms	612 KB	Output is correct
64	Correct	22 ms	620 KB	Output is correct

Subtask #4

30.0 / 60.0

#	Verdict	Execution time	Memory	Grader output
1	Correct	9 ms	260 KB	Output is correct
2	Correct	15 ms	208 KB	Output is correct
3	Correct	12 ms	384 KB	Output is correct
4	Correct	14 ms	464 KB	Output is correct
5	Partially correct	13 ms	604 KB	Output is partially correct
6	Correct	9 ms	208 KB	Output is correct
7	Correct	11 ms	388 KB	Output is correct
8	Correct	12 ms	336 KB	Output is correct
9	Correct	16 ms	336 KB	Output is correct
10	Partially correct	16 ms	592 KB	Output is partially correct
11	Partially correct	16 ms	592 KB	Output is partially correct
12	Partially correct	10 ms	656 KB	Output is partially correct
13	Partially correct	8 ms	644 KB	Output is partially correct
14	Correct	10 ms	208 KB	Output is correct
15	Correct	15 ms	208 KB	Output is correct
16	Correct	12 ms	336 KB	Output is correct
17	Correct	12 ms	288 KB	Output is correct
18	Correct	18 ms	336 KB	Output is correct
19	Correct	17 ms	444 KB	Output is correct
20	Correct	15 ms	336 KB	Output is correct
21	Correct	11 ms	256 KB	Output is correct
22	Correct	12 ms	336 KB	Output is correct
23	Correct	14 ms	384 KB	Output is correct
24	Correct	16 ms	208 KB	Output is correct
25	Correct	16 ms	384 KB	Output is correct
26	Correct	16 ms	420 KB	Output is correct
27	Correct	20 ms	512 KB	Output is correct
28	Correct	15 ms	336 KB	Output is correct
29	Correct	15 ms	336 KB	Output is correct
30	Correct	17 ms	336 KB	Output is correct
31	Correct	19 ms	336 KB	Output is correct
32	Correct	15 ms	208 KB	Output is correct
33	Correct	10 ms	208 KB	Output is correct
34	Correct	17 ms	336 KB	Output is correct
35	Correct	18 ms	356 KB	Output is correct
36	Correct	12 ms	336 KB	Output is correct
37	Correct	16 ms	456 KB	Output is correct
38	Correct	21 ms	388 KB	Output is correct
39	Correct	23 ms	496 KB	Output is correct
40	Correct	17 ms	428 KB	Output is correct
41	Correct	18 ms	436 KB	Output is correct
42	Correct	15 ms	436 KB	Output is correct
43	Partially correct	13 ms	592 KB	Output is partially correct
44	Partially correct	18 ms	592 KB	Output is partially correct
45	Partially correct	10 ms	592 KB	Output is partially correct
46	Partially correct	17 ms	592 KB	Output is partially correct
47	Partially correct	15 ms	616 KB	Output is partially correct
48	Partially correct	15 ms	604 KB	Output is partially correct
49	Partially correct	19 ms	592 KB	Output is partially correct
50	Partially correct	22 ms	620 KB	Output is partially correct
51	Partially correct	17 ms	592 KB	Output is partially correct
52	Partially correct	22 ms	592 KB	Output is partially correct
53	Partially correct	19 ms	592 KB	Output is partially correct
54	Partially correct	20 ms	592 KB	Output is partially correct
55	Partially correct	20 ms	720 KB	Output is partially correct
56	Partially correct	16 ms	592 KB	Output is partially correct
57	Partially correct	23 ms	640 KB	Output is partially correct
58	Partially correct	22 ms	716 KB	Output is partially correct
59	Partially correct	16 ms	668 KB	Output is partially correct
60	Partially correct	22 ms	596 KB	Output is partially correct
61	Partially correct	20 ms	616 KB	Output is partially correct
62	Partially correct	16 ms	716 KB	Output is partially correct
63	Partially correct	17 ms	624 KB	Output is partially correct
64	Partially correct	18 ms	628 KB	Output is partially correct
65	Partially correct	23 ms	624 KB	Output is partially correct
66	Partially correct	26 ms	592 KB	Output is partially correct
67	Partially correct	23 ms	616 KB	Output is partially correct
68	Partially correct	23 ms	640 KB	Output is partially correct
69	Partially correct	22 ms	612 KB	Output is partially correct
70	Partially correct	25 ms	612 KB	Output is partially correct
71	Partially correct	20 ms	616 KB	Output is partially correct
72	Partially correct	21 ms	616 KB	Output is partially correct
73	Partially correct	26 ms	604 KB	Output is partially correct
74	Partially correct	21 ms	620 KB	Output is partially correct
75	Partially correct	21 ms	604 KB	Output is partially correct
76	Partially correct	24 ms	592 KB	Output is partially correct
77	Partially correct	16 ms	628 KB	Output is partially correct
78	Partially correct	20 ms	712 KB	Output is partially correct
79	Partially correct	17 ms	624 KB	Output is partially correct
80	Partially correct	26 ms	624 KB	Output is partially correct
81	Partially correct	17 ms	624 KB	Output is partially correct
82	Partially correct	19 ms	592 KB	Output is partially correct