제출 #749193

#	제출 시각	아이디	문제	언어	결과	실행 시간	메모리
749193		hafo	Commuter Pass (JOI18_commuter_pass)	C++14	100 / 100	345 ms	35784 KiB

commuter_pass

#include <bits/stdc++.h>
#define ll long long
#define ull unsigned ll
#define pb push_back
#define pa pair<int, int>
#define pall pair<ll, int>
#define fi first
#define se second
#define TASK "test"
#define all(x) x.begin(), x.end()
using namespace std;

template<typename T1, typename T2> bool mini (T1 &a, T2 b) {if(a > b) a = b; else return 0; return 1;}
template<typename T1, typename T2> bool maxi (T1 &a, T2 b) {if(a < b) a = b; else return 0; return 1;}

const int MOD = 1e9 + 7;
const int LOG = 20;
const int maxn = 2e5 + 7;
const ll oo = 1e18 + 69;

int n, m, u, v, w, s, t, a, b;
ll f[4][maxn], ans, dp[2][maxn];
vector<pa> g[maxn];
vector<int> adj[2][maxn];
bool ok[maxn];

void dijkstra(int s, int id) {
    fill_n(f[id], n + 1, oo);
    f[id][s] = 0;
    priority_queue<pall, vector<pall>, greater<pall>> q;
    q.push({0, s});

    while(!q.empty()) {
        int u = q.top().se;
        ll fu = q.top().fi;
        q.pop();

        if(f[id][u] != fu) continue;

        for(auto e:g[u]) {
            int v = e.fi, w = e.se;
            if(mini(f[id][v], fu + w)) {
                q.push({fu + w, v});
            }
        }
    }
}

void dfs(int u, int id) {
    dp[id][u] = f[2][u];
    for(auto v:adj[id][u]) {
        if(dp[id][v] == -1) dfs(v, id);
        mini(dp[id][u], dp[id][v]);
    }
}

int main() {
    ios_base::sync_with_stdio(false);
    cin.tie(NULL);

    //freopen(TASK".inp", "r", stdin);
    //freopen(TASK".out", "w", stdout);

    cin>>n>>m>>s>>t>>a>>b;
    while(m--) {
        cin>>u>>v>>w;
        g[u].pb({v, w});
        g[v].pb({u, w});
    }

    dijkstra(s, 0);
    dijkstra(a, 1);
    dijkstra(b, 2);
    dijkstra(t, 3);
    ans = f[1][b];

    for(int u = 1; u <= n; u++) {
        for(auto e:g[u]) {
            int v = e.fi, w = e.se;
            if(f[0][u] + w + f[3][v] == f[0][t]) {
                adj[0][u].pb(v);
                adj[1][v].pb(u);
                ok[u] = ok[v] = 1;
            }
        }
    }

    for(int i = 0; i < 2; i++)
        for(int j = 1; j <= n; j++) dp[i][j] = -1;
    dfs(s, 0);
    dfs(t, 1);

    for(int i = 1; i <= n; i++) {
        if(!ok[i]) continue;
        mini(ans, f[1][i] + min(dp[0][i], dp[1][i]));
    }
    cout<<ans;
    return 0;
}

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