Submission #737566

#	Time	Username	Problem	Language	Result	Execution time	Memory
737566		Ronin13	Relay Marathon (NOI20_relaymarathon)	C++14	0 / 100	242 ms	37436 KiB

RelayMarathon

#include <bits/stdc++.h>
#define ll long long
#define ull unsigned ll
#define f first
#define s second
#define pii pair<int,int>
#define pll pair<ll,ll>
#define pb push_back
#define epb emplace_back
using namespace std;
const int nmax = 300001;
vector <ll> bit(nmax);

vector <vector <pll> > dp(nmax);
map <pii, bool> used;
vector <vector <pll> > g(nmax);
priority_queue <pair<ll, pii> > q;
void upd(int u, int x, ll len){
    bool tt;
    tt = false;
    for(int j = 0; j < 2; j++){
        if(dp[u][j].s == x){
            tt = true;
            if(len > dp[u][j].f) continue;
            dp[u][j].f = len;
            q.push({-dp[u][j].f, {u, dp[u][j].s}});
        }
    }
    if(!tt){
        if(len < dp[u].back().f)
        dp[u].pb({len, x}), q.push({-len, {u, x}});
    }
    sort(dp[u].begin(), dp[u].end());
    if(dp[u].size() > 2)
        dp[u].pop_back();

}

int main(){
    int n, k, m; cin >> n >> m >> k;
    for(int i = 1; i <= m; i++){
        int u, v; cin >> u >> v;
        ll w; cin >> w;
        g[u].pb({v, w});
        g[v].pb({u, w});
    }

    vector <int> sources;
    for(int i = 1 ;i <= k; i++){
        int x; cin >> x;
        sources.pb(x);
    }
   // cout << 1;
    for(int i = 1; i <= n; i++){
        for(int j = 0; j < 2; j++)
        dp[i].pb({1e18, 0});
    }
   // cout << 1;
    for(int to : sources){
        if(to <= 2) continue;
        dp[to][0] = {0, to};
        q.push({0, {to, to}});
    }
    //cout << 1;
    while(!q.empty()){
        int v = q.top().s.f, y = q.top().s.s;
        ll val = -q.top().f;
        q.pop();
        if(used[{v, y}]) continue;
        used[{v, y}] = true;
        for(auto ed : g[v]){
            int to = ed.f;
            if(to <= 2) continue;
            ll len = ed.s + val;
            upd(to, y, len);
        }
    }
    for(int i = 1; i <= n; ++i){
        for(auto to : dp[i]){
            cout << to.f << ' ';
        }
        cout << "\n";
    }
    vector <pair<ll, pii> > vec;
    for(int to : sources){
        if(to <= 2) continue;
        for(int j = 0; j < 2; j++){
            if(dp[to][j].f != 1e18)
            vec.pb({dp[to][j].f, {to, dp[to][j].s}});
        }
    }
    sort(vec.begin(), vec.end());
    int cnt[n + 1];
    fill(cnt, cnt + n + 1, 0);
    vector <pair<ll, pii> > cand;
    for(auto to : vec){
        if(cand.size() > 20) break;
        if(to.s.f == to.s.s ) continue;
        if(cnt[to.s.f] < 2 && cnt[to.s.s] < 2){
            cand.pb(to);
            cnt[to.s.f]++;
            cnt[to.s.s]++;
        }
    }
   // cout << 1;
    ll ans = 1e18;
    cand.pb({1, {1, 2}});
    for(int i = 0; i < cand.size(); i++){
        for(int j =0; j < cand.size(); j++){
            set <int> st;

            st.insert(cand[i].s.f);
            st.insert(cand[i].s.s);
            st.insert(cand[j].s.f);
            st.insert(cand[j].s.s);
            if(st.size() == 4){
                ans = min(ans, cand[i].f + cand[j].f);
            }
        }
    }
    cout << ans;
    return 0;
}

Compilation message (stderr)

RelayMarathon.cpp: In function 'int main()':
RelayMarathon.cpp:108:22: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<std::pair<long long int, std::pair<int, int> >, std::allocator<std::pair<long long int, std::pair<int, int> > > >::size_type' {aka 'long unsigned int'} [-Wsign-compare]
  108 |     for(int i = 0; i < cand.size(); i++){
      |                    ~~^~~~~~~~~~~~~
RelayMarathon.cpp:109:25: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<std::pair<long long int, std::pair<int, int> >, std::allocator<std::pair<long long int, std::pair<int, int> > > >::size_type' {aka 'long unsigned int'} [-Wsign-compare]
  109 |         for(int j =0; j < cand.size(); j++){
      |                       ~~^~~~~~~~~~~~~

• Subtask 1: 0 / 5
• Subtask 2: 0 / 12
• Subtask 3: 0 / 25
• Subtask 4: 0 / 58