Submission #1043569

#	Time	Username	Problem	Language	Result	Execution time	Memory
1043569		javotaz	LOSTIKS (INOI20_lostiks)	C++17	59 / 100	2069 ms	136828 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 = 1e9 + 7;
vector<pii> g[N];
int n, s, t, par[N], dp[(1 << M) + 4][M], p[N], kd[N], pd[N], e[N], l[N], r[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, 63, sizeof dp);
}

bool check(int v, int u, int x) {
	return ((f[l[v]][r[u]].S | x) == x) && ((f[r[u]][l[u]].S | x) == x);
}

int32_t main() {
	ios_base::sync_with_stdio(0), cin.tie(0), cout.tie(0);
	ip(), solve();
	int c = d.size();
	int ans = inf;
	for (int i = 0; i < c; i++)
		l[i] = p[par[d[i]]], r[i] = p[kd[d[i]]];
	for (int mask = 1; mask < (1 << c); ++mask) 
		for (int i = 0; i < c; ++i) 
			if ((mask >> i) & 1) {
				int x = (mask ^ (1 << i));
				if (!x) {
					if ((f[p[s]][r[i]].S | x) == x && (f[r[i]][l[i]].S | x) == x)
						dp[mask][i] = f[p[s]][r[i]].F + f[r[i]][l[i]].F;
				}
				else {
					int u = __builtin_ctz(x), y = inf;
					if (check(u, i, x))
						for (int j = 0; j < c; ++j)
							if ((x >> j) & 1 && dp[x][j] < inf)
								y = ((y < f[l[j]][r[i]].F + dp[x][j])? y : f[l[j]][r[i]].F + dp[x][j]);
					dp[mask][i] = y + f[r[i]][l[i]].F;
				}
				if ((f[l[i]][p[t]].S | mask) == mask)
					ans = min(ans, dp[mask][i] + f[l[i]][p[t]].F);
			}
	if (f[p[s]][p[t]].S == 0)
		ans = f[p[s]][p[t]].F;
	cout << ((ans >= inf)? -1 : ans) << '\n';
	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