Is Score Validator easy or hard?

Score Validator is generally considered an easy problem. The core idea is verifying a computed total using a linear scan through the input array. It focuses on basic iteration, arithmetic checks, and careful validation of constraints.

Score Validator Python/Java solution

In both Python and Java, the solution typically loops through the array of events, adds each value to a running total, and checks constraints along the way. After the loop, compare the calculated sum with the reported score. The logic is identical across languages and runs in O(n) time with O(1) space.

How to solve Score Validator in O(n)?

Traverse the scoring events once while maintaining a cumulative sum. During the iteration, validate that each event value falls within allowed constraints and update the running total. After the traversal, compare the calculated sum with the reported score to determine validity.

What is the best approach for Score Validator?

The best approach is a single-pass validation. Iterate through the list of scoring events, maintain a running sum, and verify that each event value is valid. After processing all events, check if the computed sum matches the reported score. This method runs in O(n) time and uses O(1) space.

Is Score Validator asked at Google/Amazon/Meta?

Problems that involve validating totals, cumulative sums, and input constraints appear frequently in interviews at companies like Amazon and Google. While the exact problem name may vary, the underlying pattern—single-pass validation over an array—is common in coding interviews.

What data structure is used in Score Validator?

The primary data structure is an array or list storing the scoring events. The algorithm processes the array sequentially and maintains a running total using simple variables, which keeps space usage constant.

What is the time complexity of Score Validator?

The typical solution runs in O(n) time, where n is the number of scoring events. Each event is processed exactly once while updating a running total. The algorithm uses O(1) additional space because it only stores a few counters.

3921. Score Validator - Practice Online

You are given a string array events.

Initially, score = 0 and counter = 0. Each element in events is one of the following:

"0", "1", "2", "3", "4", "6": Add that value to the total score.
"W": Increase the counter by 1. No score is added.
"WD": Add 1 to the total score.
"NB": Add 1 to the total score.

Process the array from left to right. Stop processing when either:

All elements in events have been processed, or
The counter becomes 10.

Return an integer array [score, counter], where:

score is the final total score.
counter is the final counter value.

Example 1:

Input: events = ["1","4","W","6","WD"]

Output: [12,1]

Explanation:

Event	Score	Counter
`"1"`	1	0
`"4"`	5	0
`"W"`	5	1
`"6"`	11	1
`"WD"`	12	1

Final result: [12, 1].

Example 2:

Input: events = ["WD","NB","0","4","4"]

Output: [10,0]

Explanation:

Event	Score	Counter
`"WD"`	1	0
`"NB"`	2	0
`"0"`	2	0
`"4"`	6	0
`"4"`	10	0

Final result: [10, 0].

Example 3:

Input: events = ["W","W","W","W","W","W","W","W","W","W","W"]

Output: [0,10]

Explanation:

After 10 occurrences of "W", the counter reaches 10, so processing stops. The remaining events are ignored.

Constraints:

1 <= events.length <= 1000
events[i] is one of "0", "1", "2", "3", "4", "6", "W", "WD", or "NB".