Submission #761495

#	Time	Username	Problem	Language	Result	Execution time	Memory
761495		bLIC	Commuter Pass (JOI18_commuter_pass)	C++17	100 / 100	261 ms	29496 KiB

commuter_pass

/**
 *  Author: Anil Byar
**/

#include <bits/stdc++.h>
// #include <ext/pb_ds/assoc_container.hpp>
// #include <ext/pb_ds/tree_policy.hpp>

// using namespace __gnu_pbds;
using namespace std;

// template<class T>
// using ordered_set = tree<T, null_type, less_equal<T>, rb_tree_tag, tree_order_statistics_node_update> ordered_set;



#define all(x) x.begin(), x.end()
#define rall(x) x.rbegin(), x.rend()
#define sz(x) (int)(x).size()
#define uniq(v) v.erase(unique(all(v)), v.end())
#define ft first
#define sd second
#define pb push_back
#define eb emplace_back

// Source: https://codeforces.com/blog/entry/68809
// { start
void __print(int x) {cerr << x;}
void __print(long x) {cerr << x;}
void __print(long long x) {cerr << x;}
void __print(unsigned x) {cerr << x;}
void __print(unsigned long x) {cerr << x;}
void __print(unsigned long long x) {cerr << x;}
void __print(float x) {cerr << x;}
void __print(double x) {cerr << x;}
void __print(long double x) {cerr << x;}
void __print(char x) {cerr << '\'' << x << '\'';}
void __print(const char *x) {cerr << '"' << x << '"';}
void __print(const string &x) {cerr << '"' << x << '"';}
void __print(bool x) {cerr << (x ? "true" : "false");}

template<typename T, typename V>
void __print(const pair<T, V> &x) {cerr << '{'; __print(x.first); cerr << ','; __print(x.second); cerr << '}';}
template<typename T>
void __print(const T &x) {int f = 0; cerr << '{'; for (auto &i: x) cerr << (f++ ? "," : ""), __print(i); cerr << "}";}
void _print() {cerr << "]\n";}
template <typename T, typename... V>
void _print(T t, V... v) {__print(t); if (sizeof...(v)) cerr << ", "; _print(v...);}
#ifndef ONLINE_JUDGE
#define debug(x...) cerr << "[" << #x << "] = ["; _print(x)
#else
#define debug(x...)
#endif
// } end


typedef long long ll;
typedef pair<int, int> pii;
typedef pair<ll, ll> pll;
typedef vector<int> vi;
typedef vector<pii> vii;
typedef vector<ll> vl;
typedef vector<pll> vll;
typedef vector<vi> vvi;
typedef vector<vii> vvii;
typedef vector<vl> vvl;

#define dbg if(0)

const ll MOD = 1e9+7;
const ll MOD9 = 998244353;
const ll INFLL = 1e18+5;
const int INF = 1e9;

void printbit(int x, int len) {string s="\n";while(len--){s=((x%2)?'1':'0')+s;x/=2;} cout<<s;}
ll power(ll x, ll y, ll mod){if (y==0) return 1;ll ret = power(x, y/2, mod);ret *= ret;ret%=mod;if (y&1) ret *= x;return ret%mod;}
ll modinv(ll x, ll mod = MOD) {return power(x, mod-2, mod);}

template<class T>
istream& operator>>(istream&in, vector<T>&v){
    for (T& x:v) in>>x;
    return in;
}
template<class T>
ostream& operator<<(ostream&out, vector<T>&v){
    for (T& x:v) out<<x<<' ';
    cout<<'\n';
    return out;
}
// use ?: with brackets (?:)
// check for overflow
// think about dp
// Read the statement carefully

const int maxN = 1e5+5;
const int maxK = 8001;


vll adj[maxN];
vl par[maxN];
int n, m;

vl dijkstra(int s, bool storepar){
    vl dist(n+1, INFLL);
    dist[s] = 0;
    priority_queue<pll, vll, greater<pll>> pq;
    pq.emplace(0, s);
    while(!pq.empty()){
        auto [d, u] = pq.top();
        pq.pop();

        if (d!=dist[u]) continue;
        for (auto& [v, w]:adj[u]){
            if (dist[v]>dist[u] + w){
                dist[v] = dist[u] + w;
                pq.emplace(dist[v], v);
                if (storepar){
                    par[v].clear();
                    par[v].pb(u);
                }
            } else if (dist[v] == dist[u] + w && storepar){
                par[v].pb(u);
            }
        }
    }
    return dist;
}
ll ans;
bool vis[maxN];

ll lu[maxN];
ll lv[maxN];
vl ds, dt, du, dv;
void dfs(int node, ll cu = INFLL, ll cv = INFLL){
    cu = min(cu, du[node]);
    cv = min(cv, dv[node]);
    if (vis[node]){
        ans = min(ans, cu + lv[node]);
        ans = min(ans, cv + lu[node]);
        return;
    }

    vis[node] = true;
    lu[node] = du[node];
    lv[node] = dv[node];

    for (int x:par[node]){
        dfs(x, cu, cv);
        lu[node] = min(lu[node], lu[x]);
        lv[node] = min(lv[node], lv[x]);
    }
    ans = min(ans, cu+lv[node]);
    ans = min(ans, cv+lu[node]);
}

void solve(){
    int s, t, u, v;
    cin>>n>>m;
    cin>>s>>t>>u>>v;
    for (int i = 0;i<m;i++){
        int u, v, w;cin>>u>>v>>w;
        adj[u].emplace_back(v, w);
        adj[v].emplace_back(u, w);
    }
    ds = dijkstra(s, true);
    dt = dijkstra(t, false);
    du = dijkstra(u, false);
    dv = dijkstra(v, false);

    ans = du[v];

    dfs(t);
    cout<<ans;
}

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


#define ONLINE_JUDGE
#ifndef ONLINE_JUDGE
    freopen("input.in", "r", stdin);
    freopen("output.out", "w", stdout);
    freopen("debug.dbg", "w", stderr);
    int tt = clock();
#endif

    int t=1, i = 1;
    // cin>>t;
    while(t--){
        // cout<<"Case #"<<i++<<": ";
        solve();
        cout<<'\n';
    }
#ifndef ONLINE_JUDGE
    cerr << "TIME = " << (float)(clock() - tt)/CLOCKS_PER_SEC << endl;
    tt = clock();
#endif
}

Compilation message (stderr)

commuter_pass.cpp: In function 'int main()':
commuter_pass.cpp:190:14: warning: unused variable 'i' [-Wunused-variable]
  190 |     int t=1, i = 1;
      |              ^

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