Avoid duplicates

main.go

@@ -196,6 +196,10 @@ func InsertWord(arr []word, w word) []word {
 		return append(arr, w)
 	}
 	w2 := arr[len(arr)-1]
+	if w.content == w2.content {
+		// The word is already present
+		return arr
+	}
 	if w.distance < w2.distance {
 		return append(arr, w)
 	}