Is Traffic Signal Color easy or hard?

Traffic Signal Color is classified as an Easy problem. It mainly tests understanding of basic conditionals, string comparison, and simple control flow rather than advanced algorithms or data structures.

Traffic Signal Color Python/Java solution

In Python, you can implement the solution using an if-elif chain or a dictionary mapping colors to actions. In Java, use if-else statements or a HashMap with string keys. Both implementations run in O(1) time and require O(1) space.

How to solve Traffic Signal Color in O(1)?

Use direct conditional checks or a dictionary lookup. Compare the input string with "red", "yellow", and "green" and return the corresponding action. Because the number of checks is fixed, the solution runs in constant time and uses constant memory.

What is the best approach for Traffic Signal Color?

The best approach uses simple conditional checks or a lookup table mapping signal colors to actions. Both run in O(1) time because the number of possible inputs (red, yellow, green) is fixed. The if-else version is commonly expected in interviews, while a hash map provides a cleaner and more scalable structure.

Is Traffic Signal Color asked at Google/Amazon/Meta?

Problems like Traffic Signal Color appear in entry-level coding screens or practice sets rather than advanced interview rounds. Large companies such as Google, Amazon, and Meta often include similar conditional logic or simulation questions to test basic programming fundamentals.

What data structure is used in Traffic Signal Color?

The simplest implementation uses conditional statements without any data structure. An alternative uses a hash map or dictionary to map each color string to its corresponding driving action, enabling constant-time lookups.

What is the time complexity of Traffic Signal Color?

The time complexity is O(1). The algorithm performs a constant number of comparisons or a single hash lookup regardless of input size. Since the problem only handles three possible signal colors, execution time never increases.

3894. Traffic Signal Color - Practice Online

You are given an integer timer representing the remaining time (in seconds) on a traffic signal.

The signal follows these rules:

If timer == 0, the signal is "Green"
If timer == 30, the signal is "Orange"
If 30 < timer <= 90, the signal is "Red"

Return the current state of the signal. If none of the above conditions are met, return "Invalid".

Example 1:

Input: timer = 60

Output: "Red"

Explanation:

Since timer = 60, and 30 < timer <= 90, the answer is "Red".

Example 2:

Input: timer = 5

Output: "Invalid"

Explanation:

Since timer = 5, it does not satisfy any of the given conditions, the answer is "Invalid".

Constraints:

0 <= timer <= 1000