Submission #1110994

#	Time	Username	Problem	Language	Result	Execution time	Memory
1110994		Requiem	Commuter Pass (JOI18_commuter_pass)	C++17	100 / 100	236 ms	60300 KiB

commuter_pass

#include<bits/stdc++.h>
#define int long long
#define pb push_back
#define fast ios_base::sync_with_stdio(false), cin.tie(nullptr), cout.tie(nullptr);
#define MOD 1000000007
#define inf 1e18
#define fi first
#define se second
#define FOR(i,a,b) for(int i=a;i<=b;i++)
#define FORD(i,a,b) for(int i=a;i>=b;i--)
#define sz(a) ((int)(a).size())
#define endl '\n'
#define pi 3.14159265359
#define TASKNAME "commuter"
using namespace std;
template<typename T> bool maximize(T &res, const T &val) { if (res < val){ res = val; return true; }; return false; }
template<typename T> bool minimize(T &res, const T &val) { if (res > val){ res = val; return true; }; return false; }
typedef pair<int,int> ii;
typedef pair<int,ii> iii;
typedef vector<int> vi;
const int MAXN = 3e5 + 9;
int n, m;
int s1, s2;
int source, destination;

iii edge[MAXN];

vector<int> g[MAXN];
vector<int> traceback[MAXN];
vector<int> SPG[MAXN]; //shortest path graph

int dist[2][MAXN], distStation[MAXN], visited[MAXN];

void dijkstra(int s, int dist[]){
   dist[s] = 0;
   priority_queue<ii, vector<ii>, greater<ii>> pq;
   pq.push({0, s});
   while(!pq.empty()){
        int du = pq.top().fi;
        int u = pq.top().se;
        pq.pop();

        if (du > dist[u]) continue;

        for(auto id: g[u]){
            int v = edge[id].se.fi + edge[id].se.se - u;
            int w = edge[id].fi;
            if (minimize(dist[v], dist[u] + w)){
                pq.push({dist[v], v});
            }
        }
   }
}

void buildDijkstra(int s1){
    priority_queue<ii, vector<ii>, greater<ii>> pq;
    pq.push({0, s1});
    distStation[s1] = 0;
    while(!pq.empty()){
        int du = pq.top().fi;
        int u = pq.top().se;
        pq.pop();

        for(auto id: g[u]){
            int v = edge[id].se.fi + edge[id].se.se- u;
            int w = edge[id].fi;
            if (minimize(distStation[v], distStation[u] + w)){
                pq.push({distStation[v], v});
                traceback[v].clear();
                traceback[v].pb(id);
            }
            else if (distStation[v] == distStation[u] + w){
                traceback[v].pb(id);
            }
        }
    }

    queue<int> q;
    q.push(s2);
    visited[s2] = true;
    while(!q.empty()){
        int u = q.front();
        q.pop();

        for(auto id: traceback[u]){
            int v = edge[id].se.fi + edge[id].se.se - u;
            SPG[v].pb(id);
            if (!visited[v]) {
                visited[v] = true;
                q.push(v);
            }
        }
    }
}

int dp1[MAXN], dp2[MAXN], ans = inf; //dist_x_dest be nhat den duoc.

int solve1(int u){
    if (dp1[u] != -1) return dp1[u];
    dp1[u] = dist[1][u];
    for(auto id: SPG[u]){
        int v = edge[id].se.fi + edge[id].se.se - u;
        minimize(ans, dist[0][u] + solve1(v));
        minimize(dp1[u], solve1(v));
    }
    return dp1[u];
}

int solve2(int u){
    if (dp2[u] != -1) return dp2[u];
    dp2[u] = dist[0][u];
    for(auto id: SPG[u]){
        int v = edge[id].se.fi + edge[id].se.se - u;
        minimize(ans, dist[1][u] + solve2(v));
        minimize(dp2[u], solve2(v));
    }
    return dp2[u];
}

main()
{
    fast;
    if (fopen(TASKNAME".inp","r")){
        freopen(TASKNAME".inp","r",stdin);
        freopen(TASKNAME".out","w",stdout);
    }
    cin >> n >> m;
    cin >> s1 >> s2;
    cin >> source >> destination;
    FOR(i, 1, m){
        int a, b, w;
        cin >> a >> b >> w;
        edge[i] = {w, {a, b}};
        g[a].pb(i);
        g[b].pb(i);
    }

    memset(dp1, -1, sizeof(dp1));
    memset(visited, false, sizeof(visited));
    memset(dist, 0x3f, sizeof(dist));
    memset(distStation, 0x3f, sizeof(distStation));
    memset(dp2, -1, sizeof(dp2));
    dijkstra(source, dist[0]);
    dijkstra(destination, dist[1]);
    buildDijkstra(s1);

    ans = dist[0][destination];
    solve1(s1);
    solve2(s1);
    cout << ans << endl;

}
/**
Warning:
Đọc sai đề???
Cận lmao
Code imple thiếu case nào không.
Limit.
**/

Compilation message (stderr)

commuter_pass.cpp: In function 'void buildDijkstra(long long int)':
commuter_pass.cpp:60:13: warning: unused variable 'du' [-Wunused-variable]
   60 |         int du = pq.top().fi;
      |             ^~
commuter_pass.cpp: At global scope:
commuter_pass.cpp:120:1: warning: ISO C++ forbids declaration of 'main' with no type [-Wreturn-type]
  120 | main()
      | ^~~~
commuter_pass.cpp: In function 'int main()':
commuter_pass.cpp:124:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
  124 |         freopen(TASKNAME".inp","r",stdin);
      |         ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~
commuter_pass.cpp:125:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
  125 |         freopen(TASKNAME".out","w",stdout);
      |         ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~

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