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Incremental Dijkstra

Incremental Dijkstra updates paths efficiently as graph costs change.

Quick Facts

Compact metadata for implementation and discovery.

Category
Pathfinding
Difficulty
Intermediate
Family
Pathfinding
Tier
Core
Status
Verified
Review
Source Checked
Sources
2
Formulas
0
Relationships
1
Code example
Ready
Visualization
Ready

Overview

Incremental Dijkstra is a pathfinding method that searches a graph, grid, or configuration space using costs, heuristics, or incremental updates. It is useful when route quality, replanning cost, or search speed matters more than a naive traversal.

Core Concepts

state spacepath costsearch frontierfrontiercost estimatepath reconstruction

Quick facts

Complexity

Runtime and memory behavior at a glance.

Best

O(E)

Average

O(E log V)

Worst

O(E log V)

Space

O(V)

When to Use

  • Use Incremental Dijkstra when the map, costs, and movement rules match its search assumptions.
  • Use it when route quality and search budget must be balanced explicitly.

When Not to Use

  • Avoid when the heuristic or cost model does not match the real movement constraints.
  • Avoid when dynamic updates make a simpler replanning strategy easier to validate.

What It Does

  • Searches a state space for routes
  • Uses costs, heuristics, or incremental updates
  • Returns a route or reachable region

Use Cases

  • Game navigation
  • Robotics planning
  • Route planning

Inputs

  • Graph, grid, or map
  • Start and goal
  • Costs or heuristic

Outputs

  • Path
  • Distance estimate
  • Search tree

Pseudocode

  1. 1.Initialize start state, goal state, and search records
  2. 2.Select the next frontier node using cost, heuristic, or sampling rule
  3. 3.Expand reachable neighbors or samples
  4. 4.Update path costs and parent links
  5. 5.Return the reconstructed path or failure result

Canonical Example

Input
grid with start S and goal G
Output
route from S to G or no path
Explanation
Incremental Dijkstra expands candidate states and reconstructs a path when the goal is reached.

Implementation Notes

  • Keep cost, heuristic, and parent-link updates in separate steps.
  • Test blocked, unreachable, and changing-cost maps.

Common Pitfalls

  • Using an inadmissible heuristic while expecting optimal paths gives incorrect guarantees.
  • Forgetting to update parent links makes path reconstruction fail.

Interactive Mechanism Walkthrough

2D Grid Wavefront & Trajectory

Show the frontier expanding through the map and the final path being reconstructed.

S
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G
Step 1 of 5: Initialize start state, goal state, and search records
pathfinding

Notes

Incremental Dijkstra operates in O(E log V) time and O(V) space within the Pathfinding family. Often compared with Dijkstra's Algorithm and A* Search.

Sources (2)

What each reference supports for this entry.

Introduction to Algorithms (CLRS)

Book

Algorithms textbook support for Incremental Dijkstra invariants, search ordering, correctness argument, or asymptotic analysis.

Open source

Shortest Paths: Theory and Practice

Book

Shortest-path reference supporting Dijkstra variants, reoptimization, and route-planning tradeoffs.

Explore Next

Good next jumps from the relationship graph, ranked for useful discovery.

Incremental Dijkstra is a named variant of Dijkstra's Algorithm with a more specific construction or operating tradeoff.

Tags

PathfindingGraph