Submission #1025281

#	Time	Username	Problem	Language	Result	Execution time	Memory
1025281		a_l_i_r_e_z_a	LOSTIKS (INOI20_lostiks)	C++17	59 / 100	2045 ms	323664 KiB

Main

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

#pragma GCC optimize("O3,unroll-loops")
// #pragma GCC optimize("avx2")

typedef long long ll;
typedef long double ld;
typedef pair<int, int> pii;
typedef pair<ll, ll> pll;

#define pb push_back
#define int long long
#define S second
#define F first
#define mp make_pair
#define smax(xyxy, yxy) (xyxy) = max((xyxy), (yxy))
#define smin(xyxy, yxy) (xyxy) = min((xyxy), (yxy))
#define all(xyxy) (xyxy).begin(), (xyxy).end()
#define len(xyxy) ((int)(xyxy).size())

const int maxn = 2e6 + 5, lg = 22;
const ll inf = 1e15 + 7;
ll n, s, t, w[lg], dp[(1ll << lg)][lg + 1];
pll d[lg + 1][maxn];
vector<pll> adj[maxn];
pll a[lg];

void dfs(int v, int p, int id){
    for(auto [u, e]: adj[v]){
        if(u == p) continue;
        d[id][u].F = d[id][v].F + 1;
        d[id][u].S = d[id][v].S;
        if(e != -1) d[id][u].S += 1ll << e;
        dfs(u, v, id);
    }
}

int32_t main(){
    ios_base::sync_with_stdio(0); cin.tie(0);
    
    cin >> n >> s >> t;
    int m = 0;
    for(int i = 0; i < n - 1; i++){
        int u, v, we; cin >> u >> v >> we;
        if(we == 0){
            adj[u].pb(mp(v, -1));
            adj[v].pb(mp(u, -1));
        }
        else{
            a[m] = mp(u, v);
            adj[u].pb(mp(v, m));
            adj[v].pb(mp(u, m));
            w[m] = we;
            m++;
        }
    }
    dfs(s, 0, m);
    for(int i = 0; i < m; i++){
        int v = a[i].F;
        if(d[m][a[i].S].F < d[m][a[i].F].F) v = a[i].S;
        dfs(v, 0, i);
    }
    for(int mask = (1ll << m) - 1; mask >= 0; mask--){
        for(int i = 0; i <= m; i++){
            dp[mask][i] = inf;
            int m1 = d[i][t].S, h = d[i][t].F;
            if((m1 & mask) == m1){
                dp[mask][i] = d[i][t].F;
                continue;
            }
            for(int j = 0; j < m; j++){
                if(mask & (1ll << j)) continue;
                int res = d[i][w[j]].F;
                int m2 = d[i][w[j]].S;
                if((m2 & mask) == m2){
                    int m3 = d[j][w[j]].S;
                    res += d[j][w[j]].F + dp[mask + (1ll << j)][j];
                    if((m3 & (mask + (1ll << j))) == m3) smin(dp[mask][i], res);
                }
            }
        }
    }
    if(dp[0][m] >= inf) cout << -1 << '\n';
    else cout << dp[0][m] << '\n';

    return 0;
}

Compilation message (stderr)

Main.cpp: In function 'int32_t main()':
Main.cpp:67:33: warning: unused variable 'h' [-Wunused-variable]
   67 |             int m1 = d[i][t].S, h = d[i][t].F;
      |                                 ^

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