Solution for String pattern Matching with three algoritms

[PopovMarko]

Naive, KMP, RabinKarp implement three algoritms

[coderabbitai]

Walkthrough

Adds a new Go source file providing three pattern-matching implementations (Naive, KMP, Rabin–Karp) that operate on rune slices, return starting indices of matches, and include a main with test cases; functions handle empty inputs and pattern-longer-than-text edge cases.

Changes

Cohort / File(s)	Summary
Pattern Matching Implementations challenge-23/submissions/PopovMarko/solution-template.go	Adds a new Go file with three exported functions: NaivePatternMatch, KMPSearch, and RabinKarpSearch. Each works on runes, returns match start indices, includes edge-case handling, and a main with test scaffolding. Implements LPS construction for KMP and rolling-hash+verification for Rabin–Karp.

Estimated code review effort

🎯 3 (Moderate) | ⏱️ ~25 minutes

Possibly related PRs

• Add Solution for Challenge 23 by hudazaan #557 — Adds the same exported pattern-search functions (NaivePatternMatch, KMPSearch, RabinKarpSearch) under challenge-23 submissions; likely a duplicate or closely related implementation.
• Add solution for Challenge 23 by nzamulov #564 — Also introduces the same three string-matching functions in the challenge-23 submissions area; strongly related to this change.

Poem

🐰 I hopped through runes at break of day,
Finding patterns the old-school way,
KMP lends a clever skip,
Rabin’s hash makes matches quick,
Naive hums along — hooray! ✨

🚥 Pre-merge checks | ✅ 2 | ❌ 1

❌ Failed checks (1 warning)

Check name	Status	Explanation	Resolution
Docstring Coverage	⚠️ Warning	Docstring coverage is 75.00% which is insufficient. The required threshold is 80.00%.	Write docstrings for the functions missing them to satisfy the coverage threshold.

✅ Passed checks (2 passed)

Check name	Status	Explanation
Title check	✅ Passed	The title accurately describes the main change: adding a solution with three string pattern-matching algorithms (Naive, KMP, and Rabin-Karp).
Description check	✅ Passed	The description is directly related to the changeset, identifying the three algorithms implemented (Naive, KMP, RabinKarp) despite minimal detail.

_{✏️ Tip: You can configure your own custom pre-merge checks in the settings.}

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[coderabbitai]

Actionable comments posted: 3

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ℹ️ Review info

Configuration used: Organization UI

Review profile: CHILL

Plan: Pro

📥 Commits

Reviewing files that changed from the base of the PR and between a7ac764 and 51aa66d.

📒 Files selected for processing (1)

• challenge-23/submissions/PopovMarko/solution-template.go

[coderabbitai]

🧹 Nitpick comments (2)

challenge-23/submissions/PopovMarko/solution-template.go (2)

44-55: Consider extracting shared preprocessing into a small helper.

Rune conversion and guard checks are duplicated across all three algorithms; factoring this once would reduce maintenance drift.

Also applies to: 83-94, 149-160

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143-145: Consider using int64 for rolling-hash arithmetic to support 32-bit platforms.

The rolling-hash computation at lines 28, 33–34, and 52 uses untyped integer constants (base=256, mod=101) with int-typed variables. On 32-bit architectures, expressions like base*(textHash-int(rText[i])*h) can overflow and corrupt matches. No 32-bit targets are currently tested in CI (Go 1.25.0 default is 64-bit), but using int64 improves portability.

🔧 Suggested fix

 func RabinKarpSearch(text, pattern string) []int {
-	const base = 256
-	const mod = 101 // prime number
+	const base int64 = 256
+	const mod int64 = 101 // prime number
 	res := []int{}
 	rText := []rune(text)
 	rPattern := []rune(pattern)
 	lenPattern := len(rPattern)
 	lenText := len(rText)
 	if text == "" || pattern == "" || lenPattern > lenText {
 		return []int{}
 	}
-	var patternHash, textHash, h int
+	var patternHash, textHash, h int64
 	h = 1
 	for i := 0; i < lenPattern-1; i++ {
 		h = (h * base) % mod
 	}
 	for i := range lenPattern {
-		patternHash = (base*patternHash + int(rPattern[i])) % mod
-		textHash = (base*textHash + int(rText[i])) % mod
+		patternHash = (base*patternHash + int64(rPattern[i])) % mod
+		textHash = (base*textHash + int64(rText[i])) % mod
 	}
 	for i := 0; i <= lenText-lenPattern; i++ {
 		if patternHash == textHash {
 			match := true
 			for j := range lenPattern {
 				if rText[i+j] != rPattern[j] {
 					match = false
 					break
 				}
 			}
 			if match {
 				res = append(res, i)
 			}
 		}
 		if i < lenText-lenPattern {
-			textHash = (base*(textHash-int(rText[i])*h) + int(rText[i+lenPattern])) % mod
+			textHash = (base*(textHash-int64(rText[i])*h) + int64(rText[i+lenPattern])) % mod
 			if textHash < 0 {
 				textHash += mod
 			}
 		}
 	}
 	return res
 }

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ℹ️ Review info

Configuration used: Organization UI

Review profile: CHILL

Plan: Pro

📥 Commits

Reviewing files that changed from the base of the PR and between 51aa66d and ca556c3.

📒 Files selected for processing (1)

• challenge-23/submissions/PopovMarko/solution-template.go