Submission #1094376

#	Time	Username	Problem	Language	Result	Execution time	Memory
1094376		Nurislam	Evacuation plan (IZhO18_plan)	C++17	100 / 100	440 ms	79808 KiB

plan

#include <bits/stdc++.h>
// include <ext/pb_ds/assoc_container.hpp>
// include <ext/pb_ds/tree_policy.hpp>
// using namespace __gnu_pbds;
using namespace std;
#define all(x) x.begin(), x.end()
#define pb push_back
// define ordered_set tree<int,null_type,less_equal<int>,rb_tree_tag,tree_order_statistics_node_update>
#define mpr make_pair
#define ln '\n'
void IO(string name){freopen((name+".in").c_str(),"r",stdin); freopen((name+".out").c_str(),"w",stdout);}
#define int long long
const int N = 1e5+1;
vector <pair<int,int>> g[N];
vector <int> G[N];
int lift[N][20], Mn[N][20], val[N], depth[N];
void dfs(int n, int p){
    lift[n][0] = p;
    Mn[n][0] = val[n];
    depth[n] = depth[p]+1;
    for ( int i = 1; i < 20; i++ ){
        lift[n][i] = lift[lift[n][i-1]][i-1];
        Mn[n][i] = min(Mn[n][i-1], Mn[lift[n][i-1]][i-1]);
    }
    for ( auto to: G[n] ){
        if ( to == p ) continue;
        dfs(to, n);
    }
}
int _lca(int l, int r){
    if ( depth[l] < depth[r] ) swap(l, r);
    int dif = depth[l]-depth[r], res = numeric_limits <int>::max();
    for ( int i = 19; i >= 0; i-- ){
        if ( dif >> i & 1 ){
            res = min(res, Mn[l][i]);
            l = lift[l][i];
        }
    }
    if ( l == r ) return min(res, val[l]);
    for ( int i = 19; i >= 0; i-- ){
        if ( lift[l][i] == lift[r][i] ) continue;
        res = min({res, Mn[l][i], Mn[r][i]});
        l = lift[l][i], r = lift[r][i];
    }
    res = min({res, Mn[l][1], Mn[r][1]});
    return res;
}
signed main(){
    ios_base::sync_with_stdio(false);
    cin.tie(NULL);
 
    int n, m; cin >> n >> m;
    for ( int i = 1; i <= m; i++ ){
        int x, y, w; cin >> x >> y >> w;
        g[x].pb({y, w});
        g[y].pb({x, w});
    }
    int k; cin >> k;
    priority_queue <pair<int,int>> q;
    const int inf = 1e12+1;
    vector <int> dis(n+1, inf);
    for ( int i = 1; i <= k; i++ ){
        int x; cin >> x;
        q.push({0, x});
        dis[x] = 0;
    }
    while ( !q.empty() ){
        int cur = q.top().second; q.pop();
        for ( auto [to, w]: g[cur] ){
            int new_dis = dis[cur]+w;
            if ( new_dis < dis[to] ){
                dis[to] = new_dis;
                q.push({-dis[to], to});
            }
        }
    }
    vector <int> pos(n+1), par(n+1);
    iota(all(pos), 0); iota(all(par), 0);
    sort(pos.begin()+1, pos.end(), [&](int &l, int &r){
         return dis[l] > dis[r];
    });
    for ( int i = 1; i <= n; i++ ) val[i] = dis[i];
    function <int(int)> find = [&](int x){
        return par[x] == x ? x : par[x] = find(par[x]);
    };
    auto merge = [&](int x, int y){
        x = find(x), y = find(y);
        if ( x == y ) return false;
        par[y] = x;
        return true;
    };
    vector <int> used(n+1);
    for ( auto i: pos ){
        if ( !i ) continue;
        for ( auto [to, w]: g[i] ){
            if ( !used[to] ) continue;
            if ( merge(to, i) ){
                G[to].pb(i), G[i].pb(to);
            }
        }
        used[i] = 1;
    }
    dfs(1, 0);
    int Q; cin >> Q;
    while ( Q-- ){
        int x, y; cin >> x >> y;
        cout << _lca(x, y) << ln;
    }
 
    cout << '\n';
}

Compilation message (stderr)

plan.cpp: In function 'void IO(std::string)':
plan.cpp:11:29: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   11 | void IO(string name){freopen((name+".in").c_str(),"r",stdin); freopen((name+".out").c_str(),"w",stdout);}
      |                      ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
plan.cpp:11:70: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   11 | void IO(string name){freopen((name+".in").c_str(),"r",stdin); freopen((name+".out").c_str(),"w",stdout);}
      |                                                               ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

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