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A product research organization runs controlled experiments across multiple client platforms and study tracks.
Table: Experiments
Business requirement: Analytics dashboards must always show a complete platform-study matrix with explicit zeroes for missing cells.
Task: Return the number of experiment rows for every pair in:
Output requirements:
Supported submission environments:
Experiments:
| experiment_id | platform | experiment_name |
|---------------|----------|-----------------|
| 4 | IOS | Programming |
| 13 | IOS | Sports |
| 14 | Android | Reading |
| 8 | Web | Reading |
| 12 | Web | Reading |
| 18 | Web | Programming |[
{"platform":"Android","experiment_name":"Reading","num_experiments":1},
{"platform":"Android","experiment_name":"Sports","num_experiments":0},
{"platform":"Android","experiment_name":"Programming","num_experiments":0},
{"platform":"IOS","experiment_name":"Reading","num_experiments":0},
{"platform":"IOS","experiment_name":"Sports","num_experiments":1},
{"platform":"IOS","experiment_name":"Programming","num_experiments":1},
{"platform":"Web","experiment_name":"Reading","num_experiments":2},
{"platform":"Web","experiment_name":"Sports","num_experiments":0},
{"platform":"Web","experiment_name":"Programming","num_experiments":1}
]The output is a full 3x3 grid. Missing platform-study combinations are explicitly represented with zero counts.
Experiments:
| experiment_id | platform | experiment_name |
|---------------|----------|-----------------|
| 1 | Android | Reading |
| 2 | Android | Reading |
| 3 | Android | Reading |
| 4 | Android | Sports |
| 5 | Android | Sports |
| 6 | Web | Programming |[
{"platform":"Android","experiment_name":"Reading","num_experiments":3},
{"platform":"Android","experiment_name":"Sports","num_experiments":2},
{"platform":"Android","experiment_name":"Programming","num_experiments":0},
{"platform":"IOS","experiment_name":"Reading","num_experiments":0},
{"platform":"IOS","experiment_name":"Sports","num_experiments":0},
{"platform":"IOS","experiment_name":"Programming","num_experiments":0},
{"platform":"Web","experiment_name":"Reading","num_experiments":0},
{"platform":"Web","experiment_name":"Sports","num_experiments":0},
{"platform":"Web","experiment_name":"Programming","num_experiments":1}
]Heavy concentration in a few cells must not remove empty cells from the final grid.
Experiments:
| experiment_id | platform | experiment_name |
|---------------|----------|-----------------|
| (no rows) |[
{"platform":"Android","experiment_name":"Reading","num_experiments":0},
{"platform":"Android","experiment_name":"Sports","num_experiments":0},
{"platform":"Android","experiment_name":"Programming","num_experiments":0},
{"platform":"IOS","experiment_name":"Reading","num_experiments":0},
{"platform":"IOS","experiment_name":"Sports","num_experiments":0},
{"platform":"IOS","experiment_name":"Programming","num_experiments":0},
{"platform":"Web","experiment_name":"Reading","num_experiments":0},
{"platform":"Web","experiment_name":"Sports","num_experiments":0},
{"platform":"Web","experiment_name":"Programming","num_experiments":0}
]Even with no experiment rows, the matrix still contains all nine combinations with zero values.
Constraints