Add Dijkstra

Author: coderick14

dijkstra.cpp

@@ -0,0 +1,52 @@
+#include <bits/stdc++.h>
+#define ll long long
+#define INF 1e18
+using namespace std;
+
+vector<vector<pair<ll,ll>>> adj;
+vector<ll> dist;
+set<pair<ll,ll>> active_vertices;
+
+void dijkstra(ll u) {
+	ll v,w;
+	dist[u] = 0;
+	active_vertices.insert({0, u});
+
+	while (!active_vertices.empty()) {
+		auto it = active_vertices.begin();
+		u = it->second;
+		active_vertices.erase(it);
+		for (auto neighbour : adj[u]) {
+			v = neighbour.first;
+			w = neighbour.second;
+			if (dist[u] + w < dist[v]) {
+				it = active_vertices.find({dist[v], v});
+				if (it != active_vertices.end()) {
+					active_vertices.erase(it);
+				}
+				dist[v] = dist[u] + w;
+				active_vertices.insert({dist[v], v});
+			}
+		}
+	}
+}
+
+int main() {
+	ll i, n, m, u, v, w, src;
+	cin >> n >> m;
+	adj.resize(n+1);
+	dist.assign(n+1, INF);
+
+	for (i = 0; i < m; i++) {
+		cin >> u >> v >> w;
+		adj[u].push_back({v,w});
+		adj[v].push_back({u,w});
+	}
+	cin >> src;
+
+	dijkstra(src);
+	for (i = 1; i <= n; i++) {
+		cout << i << " " << dist[i] << endl;
+	}
+	return 0;
+}