From 8552b0335791795f1f4f3298943795f4912937b2 Mon Sep 17 00:00:00 2001
From: "Brady J. Garvin" <bgarvin@cse.unl.edu>
Date: Tue, 25 Oct 2022 16:47:58 -0500
Subject: [PATCH] Designed and implmented a dynamic programming solution.
---
.../src/features/ascent/sortingByDeletion.js | 34 ++++++++++++++++++-
1 file changed, 33 insertions(+), 1 deletion(-)
diff --git a/ascent/src/features/ascent/sortingByDeletion.js b/ascent/src/features/ascent/sortingByDeletion.js
index dc52a4b..2d09ed9 100644
--- a/ascent/src/features/ascent/sortingByDeletion.js
+++ b/ascent/src/features/ascent/sortingByDeletion.js
@@ -1,3 +1,35 @@
+class Backpointer {
+ constructor(previousIndex, count) {
+ this.previousIndex = previousIndex;
+ this.count = count;
+ }
+}
+
+function chooseBackpointer(list, backpointers) {
+ const currentIndex = backpointers.length;
+ const currentElement = currentIndex < list.length ? list[currentIndex] : Infinity;
+ let best = new Backpointer(undefined, 0);
+ for (let i = 0; i < currentIndex; ++i) {
+ if (list[i] <= currentElement) {
+ const candidate = new Backpointer(i, backpointers[i].count + 1);
+ if (candidate.count > best.count) {
+ best = candidate;
+ }
+ }
+ }
+ return best;
+}
+
export function deleteToSort(list) {
- return []; // TODO: stub
+ const backpointers = [];
+ while (backpointers.length <= list.length) {
+ backpointers.push(chooseBackpointer(list, backpointers));
+ }
+ const reversedResults = [];
+ for (let current = backpointers[list.length].previousIndex;
+ current !== undefined;
+ current = backpointers[current].previousIndex) {
+ reversedResults.push(list[current]);
+ }
+ return reversedResults.reverse();
}
--
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