# KDP Exam (2026-02-18) Question 1
Solve the dining philsophers problem by using *signal and continue* monitor discipline and by using *covering condition* technique. Ensure philosphers start eating in the order of their arrival.

## Solution
```c
#define N 5 /* number of philosophers */

monitor DiningPhilosophers {
    enum { THINKING, HUNGRY, EATING };
    int phil[N];
    cond delay[N];
    queue<int> q; 
    
    bool canEat(int id) {
        return (phil[(id - 1 + N) % N] != EATING) && (phil[(id + 1) % N] != EATING)
    }
    
    void pickup(int id) {
        phil[id] = HUNGRY;
        queue.push(id);
        while (q.front() != id || ! canEat(id))
            delay[id].wait();
        q.pop();
        phil[id] = EATING;
    }
    
    void putdown(int id) {
        phil[id] = THINKING;
        for (int i = 0; i < N; i += 1)
            delay[i].signal();
    }
}
```