Three-School Unique Delegate Triplets

Easy

A national student leadership council is assembling a three-member delegation. Table: school_a student_id: unique identifier within School A student_name: unique name within School A Table: school_b student_id: unique identifier within School B student_name: unique name within School B Table: school_c student_id: unique identifier within School C student_name: unique name within School C Each delegate team must include exactly: one student from school_a, one student from school_b, one student from school_c. A team is valid only if all three selected IDs are pairwise different and all three selected names are pairwise different. Task: Return every valid team as (member_a, member_b, member_c), where each member column is the selected student_name from the corresponding school. Output requirements: Return exactly three columns in this order: member_a member_b member_c Sort by member_a, member_b, member_c in ascending order. Supported submission environments: SQL (SQLite 3.27.2) Pandas (Python)

Example 1

Input

school_a:
| student_id | student_name |
|------------|--------------|
| 1          | Alice        |
| 2          | Bob          |

school_b:
| student_id | student_name |
|------------|--------------|
| 3          | Tom          |

school_c:
| student_id | student_name |
|------------|--------------|
| 3          | Tom          |
| 2          | Jerry        |
| 10         | Alice        |

Output

[
  {"member_a":"Alice","member_b":"Tom","member_c":"Jerry"},
  {"member_a":"Bob","member_b":"Tom","member_c":"Alice"}
]

Explanation

Triplets with repeated names or repeated IDs across selected members are rejected. Only the two shown combinations satisfy both pairwise-distinct constraints.

Example 2

Input

school_a:
| student_id | student_name |
|------------|--------------|
| 11         | Zara         |

school_b:
| student_id | student_name |
|------------|--------------|
| 22         | Liam         |

school_c:
| student_id | student_name |
|------------|--------------|
| 33         | Noor         |

Output

[
  {"member_a":"Zara","member_b":"Liam","member_c":"Noor"}
]

Explanation

There is exactly one possible triplet and both IDs and names are mutually distinct, so it is valid.

Example 3

Input

school_a:
| student_id | student_name |
|------------|--------------|
| 5          | Iris         |
| 6          | Owen         |

school_b:
| student_id | student_name |
|------------|--------------|
| 5          | Miko         |
| 8          | Iris         |

school_c:
| student_id | student_name |
|------------|--------------|
| 6          | Dana         |
| 9          | Miko         |

Output

[
    {"member_a":"Owen","member_b":"Iris","member_c":"Miko"}
]

Explanation

Most combinations fail because of either ID collisions (for example A.id=6 with C.id=6) or name collisions (for example B.name=Miko with C.name=Miko). Only one triplet satisfies all six pairwise checks.

Constraints

0 <= number of rows in each of school_a, school_b, school_c <= 80
1 <= student_id <= 1000000000
student_id is unique within each individual school table
student_name is unique within each individual school table
student_name is a non-empty string with reasonable length
Cross-school overlaps of IDs and names are allowed in input
A valid output triplet must satisfy pairwise distinct IDs and pairwise distinct names
Return exactly columns: member_a, member_b, member_c
Sort output by member_a, member_b, member_c ascending
Use SQLite 3.27.2 semantics for SQL submissions
For Pandas submissions, return a DataFrame with exact columns: member_a, member_b, member_c

Preparing your editor. You can read the problem while it loads.

Three-School Unique Delegate Triplets

Easy

A national student leadership council is assembling a three-member delegation. Table: school_a student_id: unique identifier within School A student_name: unique name within School A Table: school_b student_id: unique identifier within School B student_name: unique name within School B Table: school_c student_id: unique identifier within School C student_name: unique name within School C Each delegate team must include exactly: one student from school_a, one student from school_b, one student from school_c. A team is valid only if all three selected IDs are pairwise different and all three selected names are pairwise different. Task: Return every valid team as (member_a, member_b, member_c), where each member column is the selected student_name from the corresponding school. Output requirements: Return exactly three columns in this order: member_a member_b member_c Sort by member_a, member_b, member_c in ascending order. Supported submission environments: SQL (SQLite 3.27.2) Pandas (Python)

Example 1

Input

school_a:
| student_id | student_name |
|------------|--------------|
| 1          | Alice        |
| 2          | Bob          |

school_b:
| student_id | student_name |
|------------|--------------|
| 3          | Tom          |

school_c:
| student_id | student_name |
|------------|--------------|
| 3          | Tom          |
| 2          | Jerry        |
| 10         | Alice        |

Output

[
  {"member_a":"Alice","member_b":"Tom","member_c":"Jerry"},
  {"member_a":"Bob","member_b":"Tom","member_c":"Alice"}
]

Explanation

Triplets with repeated names or repeated IDs across selected members are rejected. Only the two shown combinations satisfy both pairwise-distinct constraints.

Example 2

Input

school_a:
| student_id | student_name |
|------------|--------------|
| 11         | Zara         |

school_b:
| student_id | student_name |
|------------|--------------|
| 22         | Liam         |

school_c:
| student_id | student_name |
|------------|--------------|
| 33         | Noor         |

Output

[
  {"member_a":"Zara","member_b":"Liam","member_c":"Noor"}
]

Explanation

There is exactly one possible triplet and both IDs and names are mutually distinct, so it is valid.

Example 3

Input

school_a:
| student_id | student_name |
|------------|--------------|
| 5          | Iris         |
| 6          | Owen         |

school_b:
| student_id | student_name |
|------------|--------------|
| 5          | Miko         |
| 8          | Iris         |

school_c:
| student_id | student_name |
|------------|--------------|
| 6          | Dana         |
| 9          | Miko         |

Output

[
    {"member_a":"Owen","member_b":"Iris","member_c":"Miko"}
]

Explanation

Constraints

0 <= number of rows in each of school_a, school_b, school_c <= 80
1 <= student_id <= 1000000000
student_id is unique within each individual school table
student_name is unique within each individual school table
student_name is a non-empty string with reasonable length
Cross-school overlaps of IDs and names are allowed in input
A valid output triplet must satisfy pairwise distinct IDs and pairwise distinct names
Return exactly columns: member_a, member_b, member_c
Sort output by member_a, member_b, member_c ascending
Use SQLite 3.27.2 semantics for SQL submissions
For Pandas submissions, return a DataFrame with exact columns: member_a, member_b, member_c