Submission #1043344

#	Time	Username	Problem	Language	Result	Execution time	Memory
1043344		javotaz	LOSTIKS (INOI20_lostiks)	C++17	59 / 100	2041 ms	120716 KiB

Main

// In the Name of Allah

#include<bits/stdc++.h>
using namespace std;

#pragma GCC optimize("Ofast,unroll-loops,fast-math")
//#pragma GCC target("sse,sse2,sse3,ssse3,sse4.1,avx,avx2,sse4.2,popcnt,tune=native")

typedef long long ll;

#define F first
#define S second
#define pii pair<int, int>
#define pb push_back
#define pp pop_back
#define all(x) x.begin(), x.end()

const int N = 1e6 + 12, M = 20, inf = 2e9 + 7;
vector<pii> g[N];
int n, s, t, par[N], dp[(1 << M) + 4][M], p[N], kd[N], bt[M], sz, pd[N], e[N];
pii f[2 * M + 2][2 * M + 2];
bool mrk[N];
vector<int> v, d;

void ip() {
	cin >> n >> s >> t;
	for (int i = 1; i < n; i++) {
		int u, v, w;
		cin >> u >> v >> w;
		g[u].pb({v, w});
		g[v].pb({u, w});
	}
}

void dfs(int u) {
	for (auto i: g[u])
		if (i.F != par[u]) { 
			par[i.F] = u;
			e[i.F] = e[u] + 1;
			if (i.S) {
				pd[i.F] = d.size(), d.pb(i.F), kd[i.F] = i.S;
				v.pb(u), v.pb(i.S);
			}
			dfs(i.F);
		}
}

void dfs2(int u, int rt, int h = 0, int mask = 0, int par = -1) {
	if (mrk[u])
		f[rt][p[u]] = {h, mask};
	for (auto i: g[u])
		if (i.F != par)
			dfs2(i.F, rt, h + 1, (i.S? (mask | (1 << pd[(e[u] < e[i.F])? i.F : u])) : mask), u);
}

void solve() {
	par[s] = s;
	dfs(s);
	v.pb(s), v.pb(t);
	sort(all(v));
	v.resize(unique(all(v)) - v.begin());
	for (int i = 0; i < v.size(); i++) 
		p[v[i]] = i, mrk[v[i]] = true;
	for (int i = 0; i < v.size(); i++)
		dfs2(v[i], i);
	memset(dp, 127, sizeof dp);
	int c = d.size();
	int ans = inf;
	for (int mask = 1; mask < (1 << c); ++mask) {
		sz = 0;
		for (int i = 0; i < c; i++)
			if ((mask >> i) & 1)
				bt[sz++] = i;
		for (int id1 = 0; id1 < sz; ++id1) {
			int i = bt[id1];
			int u = d[i], ku = kd[d[i]], x = mask ^ (1 << i);
			if (__builtin_popcount(mask) == 1) {
				if (f[p[s]][p[ku]].S == x && f[p[ku]][p[par[u]]].S == x)
					dp[mask][i] = f[p[s]][p[ku]].F + f[p[ku]][p[par[u]]].F;
			}
			else {
				for (int id2 = 0; id2 < c; ++id2)
					if (id2 != id1) {
						int j = bt[id2], v = d[bt[id2]];
						if ((f[p[par[v]]][p[ku]].S | x) == x && (f[p[ku]][p[par[u]]].S | x) == x)
							dp[mask][i] = min(dp[mask][i], dp[x][j] + f[p[par[v]]][p[ku]].F + f[p[ku]][p[par[u]]].F);
					}
			}
			if ((f[p[par[u]]][p[t]].S | mask) == mask)
				ans = min(ans, dp[mask][i] + f[p[par[u]]][p[t]].F);
		}
	}
	if (f[p[s]][p[t]].S == 0)
		ans = f[p[s]][p[t]].F;
	cout << ((ans == inf)? -1 : ans) << '\n';
}

int32_t main() {
	ios_base::sync_with_stdio(0), cin.tie(0), cout.tie(0);
	ip(), solve();
	return 0;
}

Compilation message (stderr)

Main.cpp: In function 'void solve()':
Main.cpp:62:20: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   62 |  for (int i = 0; i < v.size(); i++)
      |                  ~~^~~~~~~~~~
Main.cpp:64:20: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   64 |  for (int i = 0; i < v.size(); i++)
      |                  ~~^~~~~~~~~~

• Subtask 1: 23 / 23
• Subtask 2: 36 / 36
• Subtask 3: 0 / 41