F001A. Students at the FIPS

The Poble Sec School of Informatics stores the information of its students and the marks they have obtained in the subjects they have done in this struct:

    struct Student {
        string name;             // Student's name
        int idn;                 // Student's IDN
        vector<Subject> subj;    // Subject list of the student
    };

where |Subject| is:

    struct Subject {
        string name;                // Subject's name
        double mark;                // Between 0 and 10, -1 shows NP
    };

Using these definitions, implement the function

    double mark(const vector<Student>& stu, int idn, string name);

that searches and returns the mark that the student |idn| has obtained at the subject |name|. If the student does not exist, or if he has not done the subject, or his mark is NP, the function must return $-1$ .

You also have to implement the function:

double mean(const vector<Subject>& subj);

that calculates and returns the average mark of the subjects in the vector |subj|. To calculate the average mark, NP must be ignored. If all the marks are NP or the vector is empty, the mean mark is $-1$ .

Using the previous functions, you must implement:

    void count(const vector<Students>& stu, int idn, string name, int& counter);

Precondition

There are not repeated students. In the list of subjects of each student there are not repeated subjects.

Observation

The main program is already done; do not modify it. This program reads the student’s data, then prints the result of your |count()| function for each combination student-subject of the input.

(In the instance, the average marks of Helen, Michael, Peter, Alicia, Paul, John and George are respectively 9.5, 8, 0, 5.25, $-1$ , 9.25 and $-1$ . The 2 in the output corresponds to Helen and John. The 1 corresponds to Helen. The 5 correspond to Helen, Michael, Peter, Alicia and John).

Problem information

Author: Unknown
Translator: Carlos Molina

Generation: 2026-01-25T11:52:44.814Z