Submission #465122

#	Time	Username	Problem	Language	Result	Execution time	Memory
465122		Marslai24	Commuter Pass (JOI18_commuter_pass)	C++14	100 / 100	708 ms	32272 KiB

commuter_pass

#include <bits/stdc++.h>
using namespace std;
#define int long long
#define all(x) x.begin(), x.end()
 
const int INF = 1e18, MOD = 1e9 + 7, N = 1e5 + 1;
 
void setIO(string name = ""){
    ios::sync_with_stdio(false);
    cin.tie(0);
    if(name.size()){
        freopen((name + ".in").c_str(), "r", stdin);
        freopen((name + ".out").c_str(), "w", stdout);
    }
}
using pii = pair<int, int>;
vector<pii> adj[N];
int disu[N], disv[N], diss[N], vis[N], ans, dp[2][N];

void getdis(int start, int dis[]){
    fill(vis, vis + N, false);
    priority_queue<pii> pq;
    pq.push({0, start});
    dis[start] = 0;
    while(!pq.empty()){
        int c, cur;
        tie(c, cur) = pq.top();
        pq.pop();
        if(!vis[cur]){
            dis[cur] = -c;
            vis[cur] = 1;
            for(auto nxt : adj[cur])pq.push({c - nxt.first, nxt.second});
        }
    }
}

void dijkstra(int start, int end){
    fill(vis, vis + N, false);
    fill(dp[0], dp[0] + N, INF);
    fill(dp[1], dp[1] + N, INF);
    priority_queue<pair<int, pii>> pq;
    pq.push({0, {start, 0}});
    while(!pq.empty()){
        int c, cur, par;
        pii tmp;
        tie(c, tmp) = pq.top();
        tie(cur, par) = tmp;
        pq.pop();
        if(!vis[cur]){
            vis[cur] = 1;
            dp[0][cur] = min(disu[cur], dp[0][par]);
            dp[1][cur] = min(disv[cur], dp[1][par]);
            diss[cur] = -c;
            for(auto nxt : adj[cur])pq.push({c - nxt.first, {nxt.second, cur}});
        }else if(diss[cur] == -c){
            if(min(disu[cur], dp[0][par]) + min(disv[cur], dp[1][par]) < dp[0][cur] + dp[1][cur]){
                dp[0][cur] = min(disu[cur], dp[0][par]);
                dp[1][cur] = min(disv[cur], dp[1][par]);
            }
        }
    }
    ans = min(ans, dp[0][end] + dp[1][end]);
}

signed main(){
    setIO();
    int n, m, s, t, u, v;
    cin >> n >> m >> s >> t >> u >> v;
    for(int i = 0; i < m; i++){
        int a, b, c;
        cin >> a >> b >> c;
        adj[a].push_back({c, b});
        adj[b].push_back({c, a});
    }
    getdis(u, disu);
    getdis(v, disv);
    ans = disu[v];
    dijkstra(s, t);
    dijkstra(t, s);
    cout << ans;
}

Compilation message (stderr)

commuter_pass.cpp: In function 'void setIO(std::string)':
commuter_pass.cpp:12:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   12 |         freopen((name + ".in").c_str(), "r", stdin);
      |         ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
commuter_pass.cpp:13:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   13 |         freopen((name + ".out").c_str(), "w", stdout);
      |         ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

• Subtask 1: 16 / 16
• Subtask 2: 15 / 15
• Subtask 3: 24 / 24
• Subtask 4: 45 / 45