Submission #989958

#	Time	Username	Problem	Language	Result	Execution time	Memory
989958		ranmk	Commuter Pass (JOI18_commuter_pass)	C++17	100 / 100	368 ms	33644 KiB

commuter_pass

#include <bits/stdc++.h>
using namespace std;
typedef long long int ll;

/*---------------------------------------------------------------------------------------------------------------------------*/
ll gcd(ll a, ll b) {if (b > a) {return gcd(b, a);} if (b == 0) {return a;} return gcd(b, a % b);}
ll expo(ll a, ll b, ll mod) {ll res = 1; while (b > 0) {if (b & 1)res = (res * a) % mod; a = (a * a) % mod; b = b >> 1;} return res;}
void extendgcd(ll a, ll b, ll*v) {if (b == 0) {v[0] = 1; v[1] = 0; v[2] = a; return ;} extendgcd(b, a % b, v); ll x = v[1]; v[1] = v[0] - v[1] * (a / b); v[0] = x; return;} //pass an arry of size1 3
ll mminv(ll a, ll b) {ll arr[3]; extendgcd(a, b, arr); return arr[0];} //for non prime b
ll mminvprime(ll a, ll b) {return expo(a, b - 2, b);}
bool revsort(ll a, ll b) {return a > b;}
void swap(int &x, int &y) {int temp = x; x = y; y = temp;}
ll combination(ll n, ll r, ll m, ll *fact, ll *ifact) {ll val1 = fact[n]; ll val2 = ifact[n - r]; ll val3 = ifact[r]; return (((val1 * val2) % m) * val3) % m;}
void google(int t) {cout << "Case #" << t << ": ";}
vector <ll> binary_rep (ll n){ vector <ll> ans; for(int i=0; i<31; i++){ if(n & (1<<i)){ ans.push_back((1<<i)); } } return ans; }
vector<ll> sieve(int n) {int*arr = new int[n + 1](); vector<ll> vect; for (int i = 2; i <= n; i++)if (arr[i] == 0) {vect.push_back(i); for (int j = 2 * i; j <= n; j += i)arr[j] = 1;} return vect;}
ll mod_add(ll a, ll b, ll m) {a = a % m; b = b % m; return (((a + b) % m) + m) % m;}
ll mod_mul(ll a, ll b, ll m) {a = a % m; b = b % m; return (((a * b) % m) + m) % m;}
ll mod_sub(ll a, ll b, ll m) {a = a % m; b = b % m; return (((a - b) % m) + m) % m;}
ll mod_div(ll a, ll b, ll m) {a = a % m; b = b % m; return (mod_mul(a, mminvprime(b, m), m) + m) % m;}  //only for prime m
ll phin(ll n) {ll number = n; if (n % 2 == 0) {number /= 2; while (n % 2 == 0) n /= 2;} for (ll i = 3; i <= sqrt(n); i += 2) {if (n % i == 0) {while (n % i == 0)n /= i; number = (number / i * (i - 1));}} if (n > 1)number = (number / n * (n - 1)) ; return number;} //O(sqrt(N))
// scanf("%d%d", &l[i], &r[i])
#define endl "\n"
// priority_queue <int, vector<int>, greater<int>> pq;
/*---------------------------------------------------------------------------------------------------------------------------*/

const ll MOD = 1e9 + 7;
ll N = 1e5 + 2;
ll M = 2e5 + 2;
ll ans = LLONG_MAX/2;
vector <vector <pair<ll, ll>>> adj(N);
vector <bool> visited (N, false);
vector <ll> du(N, LLONG_MAX/2), dv(N, LLONG_MAX/2), ds(N, LLONG_MAX/2), dpU(N, LLONG_MAX/2), dpV(N, LLONG_MAX/2);

void dijkstra1(ll index, vector <ll>& arr){
    priority_queue <pair <ll, ll>> pq;
    pq.push(make_pair(0, index));
    fill(visited.begin(), visited.end(), false);

    while(!pq.empty()){
        pair <ll, ll> p = pq.top();
        pq.pop();
        
        if(visited[p.second]==false){
            arr[p.second] = -p.first;
            visited[p.second] = true;
            for(auto ad: adj[p.second]) pq.push(make_pair(p.first - ad.second, ad.first));
        }
    }
}

void dijkstra2(ll start, ll end){
    priority_queue <pair <ll, pair <ll, ll>>> pq;
    dpU[0] = LLONG_MAX/2;
    dpV[0] = LLONG_MAX/2;
    fill(dpU.begin(), dpU.end(), LLONG_MAX/2);
    fill(dpV.begin(), dpV.end(), LLONG_MAX/2);
    fill(ds.begin(), ds.end(), LLONG_MAX/2);
    fill(visited.begin(), visited.end(), false);

    pq.push({0, {start, 0}});
    while(!pq.empty()){
        auto p = pq.top();
        pq.pop();

        if(visited[p.second.first]==false){
            ds[p.second.first] = -p.first;
            visited[p.second.first] = true;
            dpU[p.second.first] = min(dpU[p.second.second], du[p.second.first]);
            dpV[p.second.first] = min(dpV[p.second.second], dv[p.second.first]);

            for(auto nb: adj[p.second.first]) pq.push({p.first - nb.second, {nb.first, p.second.first}});
        }
        else if(ds[p.second.first] == -p.first){
            if(min(dpU[p.second.second], du[p.second.first]) + min(dpV[p.second.second], dv[p.second.first]) < dpU[p.second.first] + dpV[p.second.first]){
                dpU[p.second.first] = min(dpU[p.second.second], du[p.second.first]);
                dpV[p.second.first] = min(dpV[p.second.second], dv[p.second.first]);
            }
        }
        // ye dono conditions saath me hi honge priority queue me, agar ds == -p.f hai, to mtlb usse just pehle
        // ye value set hui hai since its a priority queue
    }

    ans = min(ans, dpU[end] + dpV[end]);
}

int main() {
    
    ios_base::sync_with_stdio(false);
    cin.tie(0); cout.tie(0);
    
    // #ifndef ONLINE_JUDGE
    // freopen("cbarn2.in", "r", stdin);
    // freopen("cbarn2.out", "w", stdout);
    // #endif
    
    int n, m;
    cin>>n>>m;
    int s, t, u, v;
    cin>>s>>t>>u>>v;
    for(int i=0; i<m; i++){
        int a, b, c;
        cin>>a>>b>>c;
        adj[a].push_back(make_pair(b, c));
        adj[b].push_back(make_pair(a, c));
    }

    dijkstra1(u, du);
    dijkstra1(v, dv);
    ans = du[v];
    dijkstra2(s, t);
    dijkstra2(t, s);

    cout<<ans<<endl;
    
    
}

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