Submission #1211162

#	Time	Username	Problem	Language	Result	Execution time	Memory
1211162		Madhav_1608	Commuter Pass (JOI18_commuter_pass)	C++20	15 / 100	780 ms	327680 KiB

commuter_pass

#include <iostream>
#include <stack>
#include <queue>
#include <string>
#include <algorithm>
#include <vector>
#include <map>
#include <set>
#include <climits>
#include <cmath>
#include <unordered_map>
#include <unordered_set>
#include <numeric>
#include <iomanip>
#include <cstring>
#include <stdio.h>
#include <assert.h>
using namespace std;
typedef long long ll;
typedef vector<int> vi;
typedef vector<string> vs;
typedef vector<long long> vll;
typedef pair<ll,ll> pll;
#define double long double
#define F first
#define S second
const double eps = 1e-9; 
#define FOR(i,a,b) for(long long i=a;i<b;i++)
#define all(v) v.begin(),v.end()
template <typename I>
void print(vector<I> &v){
    FOR(i,0,v.size()){cout << v[i] << " ";}
    cout << "\n";
}
ll gcd(ll a,ll b){
    if(a==0){return b;}
    else if(b==0){return a;}
    else if(a<b){return gcd(b%a,a);}
    else{return gcd(a%b,b);}
}
ll lcm(ll a,ll b){
    return (a/gcd(a,b))*b;
}
void setIO(string name = "") {
    freopen((name + ".in").c_str(), "r", stdin); // see /general/input-output
    freopen((name + ".out").c_str(), "w", stdout);
}
void init_code(){
    #ifndef ONLINE_JUDGE
    freopen("input.txt","r",stdin);
    freopen("output.txt","w",stdout);
    #endif
}
long long MAXN = 1e17;

void solve(){
    // store very big numbers may mean log2
    ll n,m;
    cin >> n >> m;
    n++;
    ll s,t;
    cin >> s >> t;
    ll u,v;
    cin >> u >> v;
    vector<vector<pll>> adj(n);
    FOR(i,0,m){
        ll a,b,c;
        cin >> a >> b >> c;
        adj[a].push_back({b,c});
        adj[b].push_back({a,c});
    }

    vector<long long> dist(n,MAXN);
    vector<vll> prev(n);
    vector<bool> visited(n,false);
    priority_queue<pair<long long,ll>,vector<pair<long long,ll>>,greater<>> pq;
    pq.push({0,s});
    dist[s] = 0;
    while(!pq.empty()){
        pair<long long,ll> c = pq.top();
        pq.pop();
        if(visited[c.S]) continue;
        visited[c.S] = true;
        for(pll &p:adj[c.S]){
            long long alt = c.F+p.S;
            if(alt<dist[p.F]){
                dist[p.F] = alt;
                prev[p.F].clear();
                prev[p.F].push_back(c.S);
                pq.push({alt,p.F});
            }
            else if(alt==dist[p.F]){
                prev[p.F].push_back(c.S);
            }
        }
    }

    vector<vector<pll>> adj1(n);
    queue<ll> q;
    q.push(t);
    while(!q.empty()){
        ll c = q.front();
        q.pop();
        for(ll i:prev[c]){
            adj1[c].push_back({i,0});
            q.push(i);
        }
    }
    prev.clear();
    dist.clear();
    visited.clear();
    dist.resize(n,MAXN);
    visited.resize(n,false);
    pq.push({0,u});
    dist[u] = 0;
    while(!pq.empty()){
        pair<long long,ll> c = pq.top();
        pq.pop();
        if(visited[c.S]) continue;
        visited[c.S] = true;
        for(pll &p:adj[c.S]){
            long long alt = c.F+p.S;
            if(alt<dist[p.F]){
                dist[p.F] = alt;
                pq.push({alt,p.F});
            }
        }
        for(pll &p:adj1[c.S]){
            long long alt = c.F+p.S;
            if(alt<dist[p.F]){
                dist[p.F] = alt;
                pq.push({alt,p.F});
            }
        }
    }    
    long long ans = dist[v];
    FOR(i,0,n){
        for(pll &p:adj1[i]){
            adj[p.F].push_back({i,0});
        }
    }
    adj1.clear();
    dist.clear();
    visited.clear();
    dist.resize(n,MAXN);
    visited.resize(n,false);
    pq.push({0,u});
    dist[u] = 0;
    while(!pq.empty()){
        pair<long long,ll> c = pq.top();
        pq.pop();
        if(visited[c.S]) continue;
        visited[c.S] = true;
        for(pll &p:adj[c.S]){
            long long alt = c.F+p.S;
            if(alt<dist[p.F]){
                dist[p.F] = alt;
                pq.push({alt,p.F});
            }
        }
    }    
    ans = min(ans,dist[v]);
    cout << ans << "\n";
}

signed main(){
    //setIO
    ios::sync_with_stdio(0);
    cin.tie(0);
    cout.tie(0);
    // init_code();
    ll t=1;
    // cin >> t;
    while(t--){
        solve();
    }
    return 0;
}

Compilation message (stderr)

commuter_pass.cpp: In function 'void setIO(std::string)':
commuter_pass.cpp:45:12: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   45 |     freopen((name + ".in").c_str(), "r", stdin); // see /general/input-output
      |     ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
commuter_pass.cpp:46:12: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   46 |     freopen((name + ".out").c_str(), "w", stdout);
      |     ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
commuter_pass.cpp: In function 'void init_code()':
commuter_pass.cpp:50:12: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   50 |     freopen("input.txt","r",stdin);
      |     ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~
commuter_pass.cpp:51:12: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   51 |     freopen("output.txt","w",stdout);
      |     ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~

• Subtask 1: 0 / 16
• Subtask 2: 15 / 15
• Subtask 3: 0 / 24
• Subtask 4: 0 / 45