Assuming there is a list of teachers and students as defined in the below sequence.

1. Teacher
2. Student
3. Student
4. Student
5. Teacher
6. Student
7. Teacher

A teacher can teach himself/herself and other student before the next teacher. Everyone in the list/sequence need to be taught. A teacher cannot teach another teacher.

Expected output is as below. The first element in the output should be read as #1 teaches 1,2,3,4 and #5 teaches 5,6 and #7 teaches 7.

[
    { 1:1,2,3,4; 5:5,6      ; 7:7   },
    { 1:1,2,3,4; 5:5        ; 7:6,7 },
    { 1:1,2    ; 5:3,4,5,6  ; 7:7   },
    { 1:1,2    ; 5:3,4,5    ; 7:6,7 },
    { 1:2,3    ; 5:4,5,6    ; 7:7   },
    { 1:2,3    ; 5:4,5      ; 7:6,7 },
    { 1:1      ; 5:2,3,4,5,6; 7:7   },
    { 1:1      ; 5:2,3,4,5  ; 7:6,7 }
]

Tried cartesian product like

var items = teachers.SelectMany(x => students.Where(p => p.Sequence < x.Sequence ), (x, y) => new { TeacherSequence = x.Sequence , StudentSequence = y.Sequence })

but this doesn’t work. Any ideas ?