Intermediate Topic 34 of 51 Algorithms
Dijkstra's Algorithm
Shortest paths from a source with non-negative weights.
How it works
Maintain tentative distances, repeatedly pick the unvisited node with the smallest distance (priority queue) and relax its edges. O((V + E) log V) with a heap.
Where it is used
GPS routing, network routing (OSPF).
Common pitfall
Fails with negative edge weights; use Bellman-Ford instead.
Where it fits in the course
Dijkstra's Algorithm is topic 34 of 51 in Algorithms, rated Intermediate. It follows Topological Sort. The next topic is Bellman-Ford Algorithm.
Practice and explore
- Open the interactive lesson, with a mini quiz.
- Take the Algorithms quiz.
- Explore the Graph Traversal visualizer: BFS, DFS and Dijkstra on a weighted graph.
How to study this topic
- Read the explanation above and restate the definition in your own words.
- Open the interactive lesson and answer its mini quiz.
- Read the common pitfall, then write a short example that avoids it.
- Check your understanding in the Algorithms quiz, and revisit the topic if you miss a question.
Frequently asked questions
What is Dijkstra's Algorithm?
Shortest paths from a source with non-negative weights. It belongs to Algorithms and is an intermediate-level topic.
Where do people use Dijkstra's Algorithm?
GPS routing, network routing (OSPF).
What is the most common mistake with Dijkstra's Algorithm?
Fails with negative edge weights; use Bellman-Ford instead.
What should I learn before this topic?
Start with Topological Sort, the topic just before it in Algorithms.
How can I practice it?
Answer the mini quiz in the interactive lesson, then take the Algorithms quiz. You can also explore Graph Traversal in the Visual Lab.
Is Dijkstra's Algorithm hard to learn?
It is an Intermediate topic. Be comfortable with the Beginner topics in this area first, then read the common pitfall carefully, since it is where most mistakes happen.
How long does it take to learn Dijkstra's Algorithm?
Most learners can read the explanation and finish the interactive lesson in under an hour. Fluency comes from applying the idea, so plan a few short practice sessions with the quiz.
Which topics are related to Dijkstra's Algorithm?
Topological Sort, Bellman-Ford Algorithm, Depth-First Search are closely connected. The full list is in the related topics section of this page.
What should I study after Dijkstra's Algorithm?
Continue with Bellman-Ford Algorithm, the next topic in Algorithms.
Related topics
- Topological Sort (Algorithms)
- Bellman-Ford Algorithm (Algorithms)
- Depth-First Search (Algorithms)
- Floyd-Warshall Algorithm (Algorithms)
- Shor's Algorithm (Emerging & Frontier Topics)
- Grover's Algorithm (Emerging & Frontier Topics)