Count Failed, Passed and Honors Exam Results From Percentage Scores
Company: Google
Role: Software Engineer
Category: Coding & Algorithms
Difficulty: easy
Interview Round: Online Assessment
Students take an exam, and each result is a percentage score. Classify every result into one of three bands and count how many results fall into each band.
### Function Signature
```python
def count_result_bands(results: list[int]) -> list[int]:
```
### Rules
- A result below 50 is **Failed**: `score < 50`.
- A result from 50 to 80, both inclusive, is **Passed without Honors**: `50 <= score <= 80`.
- A result above 80 is **Passed with Honors**: `score > 80`.
- Return a list of exactly three integers in this order: `[failed, passed_without_honors, passed_with_honors]`.
- Every result is counted in exactly one band, so the three counts sum to `len(results)`.
### Constraints
- `1 <= len(results) <= 100`
- Each `results[K]` is an integer with `0 <= results[K] <= 100`. The report states the band limits as percentages without giving the score range; this version fixes it to whole percentages from 0 to 100.
### Examples
**Example 1**
```text
Input: results = [50, 80, 81, 99, 30, 77, 67]
Output: [1, 4, 2]
```
30 is the only failed result. 50 and 80 sit exactly on the band limits and, together with 77 and 67, pass without honors. 81 and 99 pass with honors.
**Example 2**
```text
Input: results = [30, 30, 49]
Output: [3, 0, 0]
```
**Example 3**
```text
Input: results = [0, 100]
Output: [1, 0, 1]
```
Overview: A coding task that classifies a list of exam scores, given as percentages, into failed, passed without honors and passed with honors bands, and returns the three counts in a fixed order. It tests careful handling of the inclusive and exclusive boundaries at 50 and 80 percent.
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