Create 1680 longestFlightRoute(dijkastra).cpp

This code is giving tle but this is also a method to solve this problem
basically assign every node -1 weight and apply dijkastra.

Author: manitajay

cses graph/1680 longestFlightRoute(dijkastra).cpp

@@ -0,0 +1,81 @@
+// JAI BAJARANG BALI
+
+// manitianajay45
+
+// give me some sunshine, give me some rain, give me another chance to grow up once again....
+
+// sab moh maya hai....
+
+/*
+This code is giving tle but this is also a method to solve this problem
+basically assign every node -1 weight and apply dijkastra.
+*/
+
+#include <bits/stdc++.h>
+using namespace std;
+
+#define endl "\n"
+
+#define ll int
+
+
+int main()
+{
+    ios_base::sync_with_stdio(false);
+    cin.tie(NULL);
+    ll n, m;
+    cin >> n >> m;
+    vector<ll> graph[n + 1];
+    vector<ll> par(n + 1, -1);
+    vector<ll> d(n + 1, 0);
+    for (ll i = 0; i < m; i++)
+    {
+        ll u, v;
+        cin >> u >> v;
+        graph[u].push_back(v);
+    }
+    d[1] = 0;
+    par[1]=-1;
+    priority_queue<pair<ll, ll>, vector<pair<ll, ll>>, greater<pair<ll, ll>>> pq;
+    pq.push({0, 1});
+    while (!pq.empty())
+    {
+        pair<ll, ll> pr = pq.top();
+        pq.pop();
+        if (d[pr.second] < pr.first)
+        {
+            continue;
+        }
+        for (auto i : graph[pr.second])
+        {
+            if (d[i] > d[pr.second] - 1)
+            {
+                d[i] = d[pr.second] - 1;
+                pq.push({d[i], i});
+                par[i] = pr.second;
+            }
+        }
+    }
+
+    if (d[n] == 0)
+    {
+        cout << "IMPOSSIBLE" << endl;
+        return 0;
+    }
+    cout << (-1 * d[n] + 1) << endl;
+    vector<ll> ans;
+    ll nd = n;
+    while (nd != -1)
+    {
+        ans.push_back(nd);
+        nd = par[nd];
+    }
+    reverse(ans.begin(), ans.end());
+    for (auto i : ans)
+    {
+        cout << i << " ";
+    }
+    cout << endl;
+
+    return 0;
+}