Submission #1097700

#	Time	Username	Problem	Language	Result	Execution time	Memory
1097700		anhthi	Evacuation plan (IZhO18_plan)	C++14	0 / 100	123 ms	61376 KiB

plan

#include <bits/stdc++.h>

using namespace std;

#define fi first
#define se second
#define ll long long
#define mp(x, y) make_pair(x, y)
#define sz(v) ((int) (v).size())
#define all(v) (v).begin(), (v).end()
#define MASK(i) (1LL << (i))
#define BIT(x, y) (((x) >> (y)) & 1)
#define pb push_back
#define max_rng *max_element
#define min_rng *min_element
#define rep(i, n) for(int i = 1, _n = (n); i <= _n; ++i)
#define forn(i, a, b) for(int i = (a), _b = (b); i <= _b; ++i)
#define ford(i, a, b) for(int i = (a), _b = (b); i >= _b; --i)

template <class X, class Y>
    inline bool maximize(X &x, Y y) {
        return (x < y ? x = y, true : false);
    }

template <class X, class Y>
    inline bool minimize(X &x, Y y) {
        return (x > y ? x = y, true : false);
    }

template <class X>
    inline void compress(vector<X> &a) {
        sort(all(a));
        a.resize(unique(all(a)) - a.begin());
    }

int ctz(ll x) { return __builtin_ctzll(x); }
int lg(ll x) { return 63 - __builtin_clzll(x); }
int popcount(ll x) { return __builtin_popcount(x); }

mt19937_64 rng(chrono::high_resolution_clock::now().time_since_epoch().count());
ll rand(ll l, ll r) {
    return l + abs((ll) rng()) % (r - l + 1);
}

const ll oo = (ll) 1e17;
const int inf = (int) 1e9 + 7, mod = (int) 1e9 + 7;

const int mxn = 5e5 + 5, mxm = 3e2 + 5;
const int LOG = 17, BASE = 311;

void add(int &x, int y) { x += y; if (x >= mod) x -= mod; }
void sub(int &x, int y) { x -= y; if (x < 0) x += mod; }

int n, m, k, q;
struct Edge {
    int u, v, w;
} e[mxn];

int safe[mxn];
vector<pair<int, int>> g[mxn];

int dp[mxn];

struct dsu {
    int n;
    vector<int> par, sz;

    dsu(int n) : n(n) {
        par.resize(n+1);
        sz.resize(n+1,1);
        rep(i, n) par[i] = i;
    }

    int root(int u) {
        return par[u] == u ? u : par[u] = root(par[u]);
    }

    bool join(int u, int v) {
        u = root(u);
        v = root(v);
        if (u == v) return false;
        if (sz[u] < sz[v])
            swap(u, v);
        par[v] = u;
        sz[u] += sz[v];
        return true;
    }
};

vector<pair<int, int>> dag[mxn];

int h[mxn];
int par[mxn][LOG + 5];
int minval[mxn][LOG + 5];

void dfs(int u, int p) {
    forn(i, 1, LOG) {
        par[u][i] = par[ par[u][i-1] ][i-1];
        minval[u][i] = min(minval[u][i-1], minval[ par[u][i-1] ][i-1]);
    }
    for (pair<int, int> i : dag[u]) {
        int v = i.first, w = i.second;
        if (v == p) continue;

        h[v] = h[u] + 1;
        par[v][0] = u;
        minval[v][0] = w;

        dfs(v, u);
    }

    return;
}

int lca(int u, int v) {
    if (h[u] < h[v]) swap(u, v);

    int k = h[u] - h[v];
    for (; k > 0; k -= k & -k)
        u = par[u][ctz(k)];

    if (u == v) return u;

    ford(i, lg(h[u]), 0) if (par[u][i] != par[v][i]) {
        u = par[u][i]; v = par[v][i];
    }
    return par[u][0];
}
int getMin(int u, int k) {
    int ans = inf;
    for (; k > 0; k -= k & -k) {
        minimize(ans, minval[u][ctz(k)]);
        u = par[u][ctz(k)];
    }
    return ans;
}

int main(void) {

    ios_base::sync_with_stdio(0);
    cin.tie(0); cout.tie(0);

    #define TASK "walk"
    if (fopen(TASK".inp", "r")) {
        freopen(TASK".inp", "r", stdin);
        freopen(TASK".out", "w", stdout);
    }

    cin >> n >> m >> k >> q;
    rep(i, m) {
        int u, v, w;
        cin >> u >> v >> w;
        e[i] = {u, v, w};
        g[u].pb(mp(v, i));
        g[v].pb(mp(u, i));
    }

    rep(i, k) {
        int p;
        cin >> p;
        safe[p] = true;
    }
    memset(dp, 0x3f, sizeof dp);

    priority_queue<pair<ll, int>> pq;

    rep(i, n) {
        if (safe[i]) {
            dp[i] = 0;
            pq.push(mp(0, i));
        }
    }

    while (sz(pq)) {
        pair<ll, int> top = pq.top(); pq.pop();
        int u = top.se; ll dist = -top.fi;

        if (dp[u] != dist) continue;

        for (pair<int, int> i : g[u]) {
            ll d = dist + e[i.second].w;
            if (minimize(dp[i.first], d)) {
                pq.push(mp(-d, i.first));
            }
        }
    }

    struct Info {
        int u, v, w;
        bool operator < (const Info &o) const {
            return w > o.w;
        }
    };

    vector<Info> res;
    forn (i, 1, m) {
        res.pb({e[i].u, e[i].v, min(dp[e[i].u], dp[e[i].v])});
    }

    dsu d(n);
    sort(all(res));

    for (Info &cur : res) {
        if (d.join(cur.u, cur.v)) {
            dag[cur.u].pb(mp(cur.v, cur.w));
            dag[cur.v].pb(mp(cur.u, cur.w));
        }
    }

    dfs(1, 0);

    rep(i, q) {
        int u, v;
        cin >> u >> v;

        int P = lca(u, v);
        int ans = min(getMin(u, h[u] - h[P]), getMin(v, h[v] - h[P]));

        cout << ans << '\n';
    }

    return 0;
}

Compilation message (stderr)

plan.cpp: In function 'int main()':
plan.cpp:145:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
  145 |         freopen(TASK".inp", "r", stdin);
      |         ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~
plan.cpp:146:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
  146 |         freopen(TASK".out", "w", stdout);
      |         ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~

• Subtask 1: 0 / 10
• Subtask 2: 0 / 13
• Subtask 3: 0 / 12
• Subtask 4: 0 / 19
• Subtask 5: 0 / 46