moved arrays solution to new file and copied back old solution. (thes…

…e commits should be squashed)

anagram/anagram.go

@@ -2,47 +2,50 @@ package anagram
 
 import "strings"
 
-func isSubset(s, S string) bool {
-	used := make([]bool, len(S))
-OuterLoop:
-	for _, r := range s {
-		if r == ' ' {
+func FindAnagrams(dictionary []string, word string) (result []string) {
+	word = normalize(word)
+	if len(word) == 0 {
+		return nil
+	}
+
+	charDir := parseCharDic(word)
+	for _, value := range dictionary {
+		ww := normalize(value)
+		// ignore exact match or empty word(not anagram)
+		if ww == word || len(ww) == 0 {
 			continue
 		}
-		for i, R := range S {
-			if !used[i] && r == R {
-				used[i] = true
-				continue OuterLoop
-			}
+
+		if compareDics(charDir, parseCharDic(ww)) {
+			result = append(result, value)
 		}
-		return false
 	}
-	return true
+	return result
 }
 
-func nonEmpty(s string) bool {
-	for _, r := range s {
-		if r != ' ' {
-			return true
-		}
-	}
-	return false
+func normalize(s string) string {
+	return strings.Replace(strings.ToLower(s), " ", "", -1)
 }
 
-func isAnagram(s1, s2 string) bool {
-	s1 = strings.ToLower(s1)
-	s2 = strings.ToLower(s2)
-	return s1 != s2 && nonEmpty(s1) && nonEmpty(s2) && isSubset(s1, s2) && isSubset(s2, s1)
+func parseCharDic(word string) (result map[rune]int) {
+	result = make(map[rune]int)
+	for _, char := range word {
+		result[char] = result[char] + 1
+	}
+
+	return result
 }
 
-// FindAnagrams returns all the anagrams of `word` in dictionary
-func FindAnagrams(dictionary []string, word string) []string {
-	// assumes that words are short
-	result := make([]string, 0)
-	for _, w := range dictionary {
-		if isAnagram(word, w) {
-			result = append(result, w)
+func compareDics(dic1, dic2 map[rune]int) bool {
+	if len(dic1) != len(dic2) {
+		return false
+	}
+
+	for key, value := range dic1 {
+		if dic2[key] != value {
+			return false
 		}
 	}
-	return result
+
+	return true
 }

anagram/anagram_arrays.go

@@ -0,0 +1,49 @@
+package anagram
+
+import "strings"
+
+func isSubset(s, S string) bool {
+	used := make([]bool, len(S))
+OuterLoop:
+	for _, r := range s {
+		if r == ' ' {
+			continue
+		}
+		for i, R := range S {
+			if !used[i] && r == R {
+				used[i] = true
+				continue OuterLoop
+			}
+		}
+		return false
+	}
+	return true
+}
+
+func nonEmpty(s string) bool {
+	for _, r := range s {
+		if r != ' ' {
+			return true
+		}
+	}
+	return false
+}
+
+func isAnagram(s1, s2 string) bool {
+	s1 = strings.ToLower(s1)
+	s2 = strings.ToLower(s2)
+	return s1 != s2 && nonEmpty(s1) && nonEmpty(s2) && isSubset(s1, s2) && isSubset(s2, s1)
+}
+
+// FindAnagrams returns all the anagrams of `word` in dictionary.
+// Faster than a hashtable-based method for short words.
+func FindAnagrams2(dictionary []string, word string) []string {
+	// assumes that words are short
+	result := make([]string, 0)
+	for _, w := range dictionary {
+		if isAnagram(word, w) {
+			result = append(result, w)
+		}
+	}
+	return result
+}