Submission #1176302

#	Time	Username	Problem	Language	Result	Execution time	Memory
1176302		CrabCNH	Paths (BOI18_paths)	C++20	100 / 100	251 ms	69572 KiB

paths

#include <bits/stdc++.h>

#define task   "BriantheCrab"

#define int    long long
#define pii    pair <int, int>
#define fi     first
#define se     second
#define szf    sizeof
#define sz(s)  (int)((s).size())

using namespace std;

template <class T> void mini (T &t, T f) {if (t > f) t = f;}
template <class T> void maxi (T &t, T f) {if (t < f) t = f;}

const int maxN = 3e5 + 5;
const int inf = 1e18 + 7;
const int mod = 1e9 + 7;

int a[maxN];
vector <int> adj[maxN];
vector <vector <int>> dp;

bool bit (int x, int i) {
    return ((x >> i) & 1);
}

int flip (int x, int i) {
    return (x | (1 << i));
}

void solve () {
    int n, m, k;
    cin >> n >> m >> k;
    dp.resize (n + 1, vector <int> ((1 << (k)) + 1));
    for (int i = 1; i <= n; i ++) {
        cin >> a[i];
        a[i] --;
        dp[i][flip (0, a[i])] = 1;
    }
    for (int i = 1; i <= m; i ++) {
        int u, v;
        cin >> u >> v;
        adj[u].push_back (v);
        adj[v].push_back (u);
    }
    int res = 0;
    for (int mask = 0; mask < (1 << k); mask ++) {
        for (int i = 1; i <= n; i ++) {
            if (bit (mask, a[i]) == 1) {
                for (auto j : adj[i]) {
                    if (bit (mask, a[j]) == 0) {
                        dp[j][flip (mask, a[j])] += dp[i][mask];
                    }
                }
                //cout << dp[i][mask] << '\n';
                res += dp[i][mask] * (__builtin_popcount (mask) >= 2);
            }
        }
    }
    cout << res;
    return;
}

signed main () {
    cin.tie (nullptr) -> sync_with_stdio (false);
    if (fopen (task".inp", "r")) {
        freopen (task".inp", "r", stdin);
        freopen (task".out", "w", stdout);
    }
    int t = 1;
    //cin >> t;
    while (t --) {
        solve ();
    } 
    return 0;
}
// thfdgb

Compilation message (stderr)

paths.cpp: In function 'int main()':
paths.cpp:69:17: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   69 |         freopen (task".inp", "r", stdin);
      |         ~~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~
paths.cpp:70:17: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   70 |         freopen (task".out", "w", stdout);
      |         ~~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~

• Subtask 1: 23 / 23
• Subtask 2: 20 / 20
• Subtask 3: 27 / 27
• Subtask 4: 30 / 30