Submission #671544

#	Time	Username	Problem	Language	Result	Execution time	Memory
671544		Alihan_8	Evacuation plan (IZhO18_plan)	C++17	41 / 100	4082 ms	46688 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];
int val[N], n;
bool ok(int x, int y, int Mx){
    vector <int> used(n+1);
    queue <int> q; q.push(x);
    if ( min(val[x], val[y]) < Mx ) return false;
    while ( !q.empty() ){
        int cur = q.front(); q.pop();
        used[cur] = 1;
        for ( auto [to, w]: g[cur] ){
            if ( val[to] < Mx or used[to] ) continue;
            q.push(to);
        }
    }
    return used[y];
}
signed main(){
    ios_base::sync_with_stdio(false);
    cin.tie(NULL);

    int 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});
            }
        }
    }
    for ( int i = 1; i <= n; i++ ) val[i] = dis[i];
    int Q; cin >> Q;
    while ( Q-- ){
        int x, y; cin >> x >> y;
        int l = 0, r = inf;
        while ( l+1 < r ){
            int md = (l+r)>>1;
            if ( ok(x, y, md) ) l = md;
            else r = md;
        }
        cout << l << ln;
    }
    /*
    9 12
    1 9 4
    1 2 5
    2 3 7
    2 4 3
    4 3 6
    3 6 4
    8 7 10
    6 7 5
    5 8 1
    9 5 7
    5 4 12
    6 8 2
    2
    4 7
    5
    1 6
    5 3
    4 8
    5 8
    1 5
    */

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