refactor: lucky number exercises

* guess < 0 doesn't check for definitive positivity
* n := rand.Intn(guess + 1) may pick 0, a non positive integer
* remove: redundant parentheses from the loop in 06-dynamic-difficulty

13-loops/exercises/08-lucky-number-exercises/01-first-turn-winner/solution-better/main.go

@@ -45,13 +45,13 @@ func main() {
 		return
 	}
 
-	if guess < 0 {
+	if guess <= 0 {
 		fmt.Println("Please pick a positive number.")
 		return
 	}
 
 	for turn := 1; turn <= maxTurns; turn++ {
-		n := rand.Intn(guess + 1)
+		n := rand.Intn(guess) + 1
 
 		// Better, why?
 		//

13-loops/exercises/08-lucky-number-exercises/01-first-turn-winner/solution/main.go

@@ -45,13 +45,13 @@ func main() {
 		return
 	}
 
-	if guess < 0 {
+	if guess <= 0 {
 		fmt.Println("Please pick a positive number.")
 		return
 	}
 
 	for turn := 1; turn <= maxTurns; turn++ {
-		n := rand.Intn(guess + 1)
+		n := rand.Intn(guess) + 1
 
 		if n == guess {
 			if turn == 1 {

13-loops/exercises/08-lucky-number-exercises/02-random-messages/solution/main.go

@@ -45,13 +45,13 @@ func main() {
 		return
 	}
 
-	if guess < 0 {
+	if guess <= 0 {
 		fmt.Println("Please pick a positive number.")
 		return
 	}
 
 	for turn := 0; turn < maxTurns; turn++ {
-		n := rand.Intn(guess + 1)
+		n := rand.Intn(guess) + 1
 
 		if n == guess {
 			switch rand.Intn(3) {

13-loops/exercises/08-lucky-number-exercises/03-double-guesses/solution/main.go

@@ -54,7 +54,7 @@ func main() {
 		}
 	}
 
-	if guess < 0 || guess2 < 0 {
+	if guess <= 0 || guess2 <= 0 {
 		fmt.Println("Please pick positive numbers.")
 		return
 	}
@@ -65,7 +65,7 @@ func main() {
 	}
 
 	for turn := 0; turn < maxTurns; turn++ {
-		n := rand.Intn(min + 1)
+		n := rand.Intn(min) + 1
 
 		if n == guess || n == guess2 {
 			fmt.Println("🎉  YOU WIN!")

13-loops/exercises/08-lucky-number-exercises/04-verbose-mode/solution/main.go

@@ -53,13 +53,13 @@ func main() {
 		return
 	}
 
-	if guess < 0 {
+	if guess <= 0 {
 		fmt.Println("Please pick a positive number.")
 		return
 	}
 
 	for turn := 1; turn <= maxTurns; turn++ {
-		n := rand.Intn(guess + 1)
+		n := rand.Intn(guess) + 1
 
 		if verbose {
 			fmt.Printf("%d ", n)

13-loops/exercises/08-lucky-number-exercises/05-enough-picks/solution/main.go

@@ -45,7 +45,7 @@ func main() {
 		return
 	}
 
-	if guess < 0 {
+	if guess <= 0 {
 		fmt.Println("Please pick a positive number.")
 		return
 	}
@@ -56,7 +56,7 @@ func main() {
 	}
 
 	for turn := 0; turn < maxTurns; turn++ {
-		n := rand.Intn(min + 1)
+		n := rand.Intn(min) + 1
 
 		if n == guess {
 			fmt.Println("🎉  YOU WIN!")

13-loops/exercises/08-lucky-number-exercises/06-dynamic-difficulty/solution/main.go

@@ -45,13 +45,13 @@ func main() {
 		return
 	}
 
-	if guess < 0 {
+	if guess <= 0 {
 		fmt.Println("Please pick a positive number.")
 		return
 	}
 
-	for turn := (maxTurns + guess/4); turn > 0; turn-- {
+	for turn := maxTurns + guess/4; turn > 0; turn-- {
-		n := rand.Intn(guess + 1)
+		n := rand.Intn(guess) + 1
 
 		if n == guess {
 			fmt.Println("🎉  YOU WIN!")