"Longest Duplicate Substring" hard task No 1044 not accepted yet, experimenting

1044-longest-duplicate-substring.go

@@ -1,5 +1,7 @@
 package main
 
+import "sync"
+
 func LongestDupSubstringBruteforce(s string) string {
 	strLen := len(s)
 	if strLen < 2 {
@@ -135,6 +137,158 @@ func LongestDupSubstringSmartforceMark2(s string) string {
 	return res
 }
 
-func LongestDupSubstring(s string) string {
-	return LongestDupSubstringSmartforceMark2(s)
+func LongestDupSubstringBruteforceReversedMark2(s string) string {
+	strLen := len(s)
+	if strLen < 2 {
+		return ""
+	}
+
+	res := ""
+	for ln := strLen - 1; ln > 0; ln-- {
+
+		if ln < len(res) {
+			break
+		}
+
+		for i := 0; i < strLen-ln; i++ {
+			word1 := s[i : i+ln]
+			for j := i + 1; j+ln <= strLen; j++ {
+				word2 := s[j : j+ln]
+				if word1 == word2 {
+					if len(res) < len(word1) {
+						res = word1
+					}
+					break
+				}
+			}
+		}
+	}
+	return res
+}
+
+func LongestDupSubstringSmartforceMark3(s string) string {
+	strLen := len(s)
+	if strLen < 2 {
+		return ""
+	}
+
+	indicesNext := []int{}
+	indicesAll := []int{}
+
+	for j := 0; j < strLen; j++ {
+		indicesAll = append(indicesAll, j)
+	}
+
+	res := ""
+	for i := 0; i < strLen-len(res); i++ {
+		indicesCurrent := indicesAll[i+1:]
+
+		for ln := 1; ln <= strLen-i; ln++ {
+
+			word1 := s[i : i+ln]
+
+			for _, index := range indicesCurrent {
+				if index+ln > strLen {
+					continue
+				}
+
+				if s[i+ln-1] == s[index+ln-1] {
+					if len(res) < len(word1) {
+						res = word1
+					}
+					indicesNext = append(indicesNext, index)
+				}
+			}
+
+			indicesCurrent = indicesNext
+			indicesNext = []int{}
+		}
+	}
+
+	return res
+}
+
+func LongestDupSubstringSmartforceMark3Goroutine(s string, from int, to int) string {
+	strLen := len(s)
+	if strLen < 2 {
+		return ""
+	}
+
+	indicesNext := []int{}
+	indicesAll := []int{}
+
+	for j := 0; j < strLen; j++ {
+		indicesAll = append(indicesAll, j)
+	}
+
+	res := ""
+	for i := from; (i < to) && (i < strLen-len(res)); i++ {
+		indicesCurrent := indicesAll[i+1:]
+
+		for ln := 1; ln <= strLen-i; ln++ {
+
+			word1 := s[i : i+ln]
+
+			for _, index := range indicesCurrent {
+				if index+ln > strLen {
+					continue
+				}
+
+				if s[i+ln-1] == s[index+ln-1] {
+					if len(res) < len(word1) {
+						res = word1
+					}
+					indicesNext = append(indicesNext, index)
+				}
+			}
+
+			indicesCurrent = indicesNext
+			indicesNext = []int{}
+		}
+	}
+
+	return res
+}
+
+func LongestDupSubstringGoroutines(s string) string {
+	threads := 24
+	results := make([]string, threads)
+	interval := len(s) / threads
+
+	if interval < (800 / threads) {
+		return LongestDupSubstringSmartforceMark3Goroutine(s, 0, len(s))
+	}
+
+	wg := new(sync.WaitGroup)
+	wg.Add(threads)
+
+	for i := 0; i < threads-1; i++ {
+		go func(input int) {
+			results[input] = LongestDupSubstringSmartforceMark3Goroutine(s, input*interval, input*interval+interval)
+			wg.Done()
+		}(i)
+	}
+
+	go func(input int) {
+		results[input] = LongestDupSubstringSmartforceMark3Goroutine(s, input*interval, len(s))
+		wg.Done()
+	}(threads - 1)
+
+	wg.Wait()
+
+	resLen := -1
+	res := ""
+
+	for _, w := range results {
+		if len(w) > resLen {
+			resLen = len(w)
+			res = w
+		}
+	}
+
+	return res
+}
+
+func LongestDupSubstring(s string) string {
+	return LongestDupSubstringGoroutines(s)
 }