CSES Flight Routes

Time Complexity: $\mathcal{O}(mk\log (mk))$

Maintain a priority queue of the $k$ best distances found for each vertex. We'll iterate through the adjacency list of each vertex at most $k$ times.

int n,m,k;
priority_queue<ll> bes[MX];
vector<pii> adj[MX];
priority_queue<pair<ll,int>,vector<pair<ll,int>>,greater<pair<ll,int>>> pq;
 
int main() {
    ios_base::sync_with_stdio(0); cin.tie(0);
    cin >> n >> m >> k;
    F0R(i,m) {
        int a,b,c; cin >> a >> b >> c;