From 41bd2884750aa9c549cc1414848c0dfa0184878e Mon Sep 17 00:00:00 2001
From: "Brady J. Garvin" <bgarvin@cse.unl.edu>
Date: Wed, 11 Oct 2023 13:50:27 -0500
Subject: [PATCH] Recorded work from Wednesday.
---
greedy-algorithms/notes.md | 24 +++++++++----------
.../src/features/fueling/solver.js | 6 ++---
2 files changed, 15 insertions(+), 15 deletions(-)
diff --git a/greedy-algorithms/notes.md b/greedy-algorithms/notes.md
index 09b242b..2e3a406 100644
--- a/greedy-algorithms/notes.md
+++ b/greedy-algorithms/notes.md
@@ -55,10 +55,10 @@ Problem: Given a sequence of fueling sites, the distances between consecutive si
## DAG
-* Vertices (situations):
- * Locations
* Edges (actions):
* Ways to advance to a location up to `range` units of distance away
+* Vertices (situations):
+ * Locations
* Edge weights (optional):
* Distance to the next location
* Topological order:
@@ -212,23 +212,23 @@ Problem: Given frequencies for a set of symbols, create a lossless binary encodi
## DAG
-* Vertices (situations):
- * …
* Edges (actions):
- * …
-* Edge weights (optional):
- * …
+ * Combine two parts (sets of symbols) and record bits for the combination that we did
+* Vertices (situations):
+ * Partitions of the symbols
+* Edge weights:
+ * Total frequency of the combined set
* Topological order:
- * …
+ * By decreasing number of parts
* Goal:
- * …
+ * Find the shortest path from having all sets separated to having all sets combined into one part
## Choosing a Forward Edge
* Direct solution:
- * …
- * …
- * …
+ * Choose the lowest-frequency part
+ * Choose the second-lowest-frequency part
+ * Follow the edge that combines those parts
## Example
diff --git a/greedy-algorithms/src/features/fueling/solver.js b/greedy-algorithms/src/features/fueling/solver.js
index 1d81f06..b97bec0 100644
--- a/greedy-algorithms/src/features/fueling/solver.js
+++ b/greedy-algorithms/src/features/fueling/solver.js
@@ -11,9 +11,9 @@ export function planFuelings(gaps, range) {
const destination = gaps.length;
while (results[results.length - 1] < destination) {
let best = undefined;
- for (let distance = …, candidate = …;
- distance < … && candidate < …;
- distance += …, candidate += …) {
+ for (let distance = 0, candidate = results[results.length - 1];
+ distance <= range && candidate <= destination;
+ distance += gaps[candidate], ++candidate) {
best = candidate;
}
results.push(best);
--
GitLab