Submission #1087727

#	Time	Username	Problem	Language	Result	Execution time	Memory
1087727		InvMOD	Commuter Pass (JOI18_commuter_pass)	C++14	100 / 100	206 ms	29356 KiB

commuter_pass

#include <bits/stdc++.h>
using namespace std;

#define fi first
#define se second
#define gcd __gcd
#define siz(v) v.size()
#define pb push_back
#define pi pair<int,int>
#define all(v) (v).begin(), (v).end()
#define FOR(i, a, b) for(int i = (a); i <= (b); i++)
///#define int long long

using ll = long long;
using ld = long double;
using ull = unsigned long long;

template<typename T> bool ckmx(T &a, T b){if(a < b) return a = b, true; return false;}
template<typename T> bool ckmn(T &a, T b){if(a > b) return a = b, true; return false;}

const int N = 2e5+5;
const ll MOD = 1e9+7;
const ll inf = 1e18;


int n, m, S, T, U, V, vis[N];
ll d[4][N], dp[2][N], answer;
vector<pair<int,ll>> adj[N];

void Dijk(int source, int id){
    for(int i = 1; i <= n; i++){
        d[id][i] = (i == source ? 0 : inf);
    }

    priority_queue<pair<ll,int>> pq;
    pq.push(make_pair(0, source));

    while(!pq.empty()){
        pair<ll,int> t = pq.top(); pq.pop();

        if(t.fi > d[id][t.se]) continue;

        int x = t.se;
        for(pair<int,ll> e : adj[x]){
            int v = e.fi; ll w = e.se;
            if(d[id][v] > d[id][x] + w){
                d[id][v] = d[id][x] + w;
                pq.push(make_pair(-d[id][v], v));
            }
        }
    }
    return;
}

bool inShortest(int u, int v, ll w){
    return d[0][u] + d[1][v] + w == d[0][T];
}

void dfs(int x)
{
    dp[0][x] = min(dp[0][x], d[2][x]);
    dp[1][x] = min(dp[1][x], d[3][x]);

    vis[x] = true;
    for(pair<int,ll> e : adj[x]){
        int v = e.fi; ll w = e.se;
        if(inShortest(x, v, w)){
            if(!vis[v]){
                dfs(v);
            }
            dp[0][x] = min(dp[0][x], dp[0][v]);
            dp[1][x] = min(dp[1][x], dp[1][v]);
        }
    }

    answer = min(answer, dp[0][x] + d[3][x]);
    answer = min(answer, dp[1][x] + d[2][x]);
    return;
}

void solve()
{
    cin >> n >> m;
    cin >> S >> T >> U >> V;

    for(int i = 1; i <= m; i++){
        int u,v,w; cin >> u >> v >> w;
        adj[u].push_back(make_pair(v, w));
        adj[v].push_back(make_pair(u, w));
    }

    Dijk(S, 0), Dijk(T, 1);
    Dijk(U, 2), Dijk(V, 3);

    for(int i = 1; i <= n; i++){
        dp[0][i] = inf;
        dp[1][i] = inf;
    }

    answer = d[2][V];
    dfs(S);

    cout << answer <<"\n";
}

signed main()
{
    ios_base::sync_with_stdio(0);
    cin.tie(0);
    cout.tie(0);

    #define name "InvMOD"
    if(fopen(name".INP", "r")){
        freopen(name".INP","r",stdin);
        freopen(name".OUT","w",stdout);
    }

    int t = 1; //cin >> t;
    while(t--) solve();
    return 0;
}

Compilation message (stderr)

commuter_pass.cpp: In function 'int main()':
commuter_pass.cpp:114:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
  114 |         freopen(name".INP","r",stdin);
      |         ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~
commuter_pass.cpp:115:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
  115 |         freopen(name".OUT","w",stdout);
      |         ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~

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