Add solution for Challenge 23 by JoQCorreia

challenge-23/submissions/JoQCorreia/solution-template.go

@@ -0,0 +1,197 @@
+package main
+
+import (
+	"fmt"
+)
+
+func main() {
+	// Sample texts and patterns
+	testCases := []struct {
+		text    string
+		pattern string
+	}{
+		{"ABABDABACDABABCABAB", "ABABCABAB"},
+		{"AABAACAADAABAABA", "AABA"},
+		{"GEEKSFORGEEKS", "GEEK"},
+		{"AAAAAA", "AA"},
+	}
+
+	// Test each pattern matching algorithm
+	for i, tc := range testCases {
+		fmt.Printf("Test Case %d:\n", i+1)
+		fmt.Printf("Text: %s\n", tc.text)
+		fmt.Printf("Pattern: %s\n", tc.pattern)
+
+		// Test naive pattern matching
+		naiveResults := NaivePatternMatch(tc.text, tc.pattern)
+		fmt.Printf("Naive Pattern Match: %v\n", naiveResults)
+
+		// Test KMP algorithm
+		kmpResults := KMPSearch(tc.text, tc.pattern)
+		fmt.Printf("KMP Search: %v\n", kmpResults)
+
+		// Test Rabin-Karp algorithm
+		rkResults := RabinKarpSearch(tc.text, tc.pattern)
+		fmt.Printf("Rabin-Karp Search: %v\n", rkResults)
+
+		fmt.Println("------------------------------")
+	}
+}
+
+// NaivePatternMatch performs a brute force search for pattern in text.
+// Returns a slice of all starting indices where the pattern is found.
+func NaivePatternMatch(text, pattern string) []int {
+
+	pIndx := []int{}
+
+	if len(text) == 0 || len(pattern) == 0 || len(pattern) > len(text) {
+		return pIndx
+	}
+
+	for i := 0; i <= len(text)-len(pattern); i++ {
+
+		j := 0
+
+		for j < len(pattern) && text[i+j] == pattern[j] {
+			j++
+		}
+
+		if j == len(pattern) {
+			pIndx = append(pIndx, i)
+		}
+	}
+
+	return pIndx
+}
+
+// KMPSearch implements the Knuth-Morris-Pratt algorithm to find pattern in text.
+// Returns a slice of all starting indices where the pattern is found.
+func KMPSearch(text, pattern string) []int {
+
+    matches := []int{}
+   if len(text) == 0 || len(pattern) == 0 || len(pattern) > len(text) {
+        return matches
+    }
+
+	lps := func(pattern string) []int {
+		// creating the longest prefix from pattern for processing string
+
+		leng := 0
+		res := make([]int, len(pattern))
+		res[0] = 0
+		i := 1
+
+		for i < len(pattern) {
+			if pattern[i] == pattern[leng] {
+				leng++
+				res[i] = leng
+				i++
+			} else {
+				if leng != 0 {
+					leng = res[leng-1]
+				}
+				res[i] = 0
+				i++
+
+			}
+
+		}
+
+		return res
+	}
+
+	lenT := len(text)
+	lenP := len(pattern)
+
+	i := 0
+	j := 0
+
+	for i < lenT {
+		if text[i] == pattern[j] {
+			i++
+			j++
+
+		}
+
+		if j == lenP {
+			matches = append(matches, (i - j))
+			j = lps(pattern)[j-1]
+
+		} else if i < lenT && pattern[j] != text[i] {
+
+			if j != 0 {
+				j = lps(pattern)[j-1]
+			} else {
+				i++
+			}
+		}
+	}
+
+	return matches
+}
+
+// RabinKarpSearch implements the Rabin-Karp algorithm to find pattern in text.
+// Returns a slice of all starting indices where the pattern is found.
+func RabinKarpSearch(text, pattern string) []int {
+	matches := []int{}
+
+	// Handle edge cases
+	if len(pattern) == 0 || len(text) < len(pattern) {
+		return matches
+	}
+
+	n := len(text)
+	m := len(pattern)
+
+	// Large prime number to avoid hash collisions
+	prime := 101
+
+	// Base value for the hash function
+	base := 256
+
+	// Hash value for pattern and initial window
+	patternHash := 0
+	windowHash := 0
+
+	// Highest power of base that we need
+	h := 1
+	for i := 0; i < m-1; i++ {
+		h = (h * base) % prime
+	}
+
+	// Calculate initial hash values
+	for i := 0; i < m; i++ {
+		patternHash = (base*patternHash + int(pattern[i])) % prime
+		windowHash = (base*windowHash + int(text[i])) % prime
+	}
+
+	// Slide the pattern over text one by one
+	for i := 0; i <= n-m; i++ {
+		// Check if hash values match
+		if patternHash == windowHash {
+			// Verify the match character by character
+			match := true
+			for j := 0; j < m; j++ {
+				if text[i+j] != pattern[j] {
+					match = false
+					break
+				}
+			}
+			if match {
+				matches = append(matches, i)
+			}
+		}
+
+		// Calculate hash value for next window
+		if i < n-m {
+			windowHash = (base*(windowHash-int(text[i])*h) + int(text[i+m])) % prime
+
+			// Ensure we only have positive hash values
+			if windowHash < 0 {
+				windowHash += prime
+			}
+		}
+	}
+
+	return matches
+}