2025-08-03: checkpoint

README.md

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+# Maxflow-rs
+
+## Idea
+
+- Generate StableGraph (petgraph)
+    - run algo on that
+- Create a custom to_graph method which displays a maxflow graph
+
+TODOs
+- [ ] Implementation of Algos:
+    - [x] Ford-Fulkersson (DFS zur Berechnung des flusserhöhenden/augmentierenden Pfads)
+    - [x] Edmonds-Karp (BFS zur Berechnung des flusserhöhenden/augmnetierenden Pfads)
+    - [x] Dinic
+    - [ ] Goldberg-Tarjan/Preflow-Push
+- [ ] Step-by-step implementation for all algos
+    - [x] Ford-Fulkerson
+    - [x] Edmonds-Karp
+    - [x] Dinic
+    - [ ] Goldberg-Tarjan/Preflow-Push
+- [x] Mark edges which have active flows with a color
+- [x] Move GUI Graph conversion to a trait of StableGraph
+- [ ] Add graph positioning strategy which looks "nicer"#
+    - [x] Only insert nodes which are at least a distance of 40 away (default)
+    - [ ] Pseudo-random node positioning strategy
+- [ ] Handle residual edges properly
+    - [x] Add display option for residual edges
+- [x] Only show active flows (filter all edges with f=0)
+- [ ] Show normal vs residual graph
+- [x] When increasing flows, handle residual path
+- [ ] Add unit tests
+    - [ ] With small problems to prove correctness
+    - [ ] For Benchmarking the algos
+    - [ ] Check validity of the generated flows (incoming flows = outgoing flows; flow <= capacity)
+- [ ] Add info display pane
+    - [x] is valid flow? (add trait to graph)
+    - [x] current total flow (add trait to calculate)
+    - [ ] number of steps
+- [ ] implement PartialEq for StableGraph (not really possible -> how do you compare graphs?)
+- [ ] Step-by-step vizualisation with choosable time delay
+- [ ] Dinic: add GUI options to show Layer Graph and Blocking flow
+- [ ] Goldberg-Tarjan: show distance labels at nodes
+- [x] change GUI colors to accomodate color-blindness (blue-yellow rather than red-green)
+- [x] remove display option for residual graph -> this should be the default
+
+DFS: Stack
+BFS: Queue
+
+Bugs:
+- [x] if I generate a new graph, the algo runs on the old graph
+- [x] if I click reset & then step, the algo runs in one step
+- [x] when using edmonds karp the updated flow isn't displayed correctly
+- [ ] the capacity on residual edges also gets displayed when using 
+
+Residual Graph:
+- parallel arcs in the same direction can be summarized into a single arc by summing up the capcities
+- 
+
+TODOs:
+- [x] gui colors in yellow blue (should be easy)
+- [x] no residual graph option, residual graph is default (medium, bit of effort)
+    - [ ] do we need to delete the graph field in algos & use residual_graph instead?
+    - [ ] check correctness of all algos by testing a small sample#
+- [ ] gui display options (medium)
+    - [ ] layer graph (done - TODO: check if correct) & blocking flow (for Dinic)
+    - [ ] goldberg-tarjan: push-relabel step - current pre-flow, flow change in every step
+- [x] add time delay for algorithm (hard due to multithreading)
+    - [ ] fix glitchy graph display (somewhere in update_graph function)
+- [ ] implement goldberg tarjan (hard)
+    - [x] fix residual edges: algo pushes flows back but increases flow on the residual edge instead of decreasing the reverse edge
+    - [ ] fix loops: somehow the algo produces loops towards the source node (not critical for calculating the total flow, but should be fixed)
+    - [ ] big tests sometimes fail for goldberg-tarjan (panic when reading node from distance labelling)
+- [x] make MaxflowAlgorithm object-safe (remove from_problem & implement it per struct, then create a generic wrapper which creates new instances for each specific algorithm)
+- [ ] add unit test environment (hard)
+    - [x] callable from gui
+    - [x] several test tuples [number of problems, node count, max capacity]
+    - [x] split MaxflowProblem:new into two functions (one for display, one for test environment)
+    - [x] apply to every algo
+    - [x] große testumgebung
+    - [x] testfunktion in seperatem thread ausführen, damit programm nicht hängt
+    - [ ] check for: 
+        - [x] flusserhaltung
+        - [x] kapazitätsbedingungen
+        - [ ] saturierter schritt
+    - [ ] testumgebung durch änderungen der lösung automatisch überprüfen (korrektheit, optimalität)
+- [x] reduce warnings
+
+
+thread '<unnamed>' panicked at src/graph.rs:191:31
+attempt to subtract with overflow
+note: run with `RUST_BACKTRACE=1` environment variable to display a backtrace
+
+thread '<unnamed>' panicked at src/algorithms/goldberg_tarjan.rs:109:238:
+No distance label found
+note: run with `RUST_BACKTRACE=1` environment variable to display a backtrace