Dijkstra implementation in C++

dijkstra.cpp

#include <bits/stdc++.h>

using namespace std;
typedef long long ll;

struct item {
    ll node;
    ll weight;
    bool operator<(const item &y) const { return weight > y.weight; }
};

vector<ll> dijkstra(vector<vector<item>> &graph, ll n) {
    vector<ll> dist(n + 1, LLONG_MAX);
    dist[1] = 0;
    priority_queue<item> pq;
    pq.push({1, 0});
    while (!pq.empty()) {
        item x = pq.top();
        pq.pop();
        if (x.weight != dist[x.node]) continue;
        for (item i : graph[x.node]) {
            if (x.weight + i.weight < dist[i.node]) {
                dist[i.node] = x.weight + i.weight;
                pq.push({i.node, x.weight + i.weight});
            }
        }
    }
    return dist;
}

int main() {
    ios::sync_with_stdio(0);
    cout.tie(0);
    cin.tie(0);
    ll n, m;
    cin >> n >> m;
    vector<vector<item>> graph(n + 1);
    while (m--) {
        ll a, b, w;
        cin >> a >> b >> w;
        graph[a].push_back({b, w});
    }
    vector<ll> dist = dijkstra(graph, n);
    for (ll i = 1; i <= n; i++) {
        cout << dist[i] << ' ';
    }
}