The question of the Philosopher's meal

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1 #defineN 5/* Number of philosophers */2 #defineTheir neighbourhood number of left (i+n-1)%N/* I */3 #defineRight (i+ 1)%N/* I number */4 #defineThinking 0/* philosopher in thinking * *5 #defineHungry 1/* philosopher tries to pick up a fork */6 #defineEATING 2/* Philosopher's Dinner * *7typedefintSemaphore/*Signal Volume*/8 intState[n];/*record each philosopher's state*/ 9Semaphore Mutex =1;/*Mutual exclusion of critical sections*/TenSemaphore S[n];/*each philosopher a semaphore*/ One  A voidPhilosopher (intI/*I: Philosopher number, from 0 to N-1*/  - {  -      while(TRUE) {/*Infinite Loops*/ theThink ();/*Philosophers Thinking*/ -Take_ Forks (i);/*Test if the fork is available*/ -Eat ();/*Philosophers Dine*/ -Put_ Forks (i);/*put the fork back on the table*/  + } - } +  A voidTake_forks (intI at {   -Down (&mutex);/*Enter the critical section*/  -State[i] = hungry;/*record philosopher I in a state of starvation*/  -Test (i);/*try to get two forks*/  -Up (&mutex);/*Exit critical Section*/  -Down (&s[i]);/*If you don't get the fork you need, it's blocked.*/  in } -   to voidPut_forks (i) + {  -Down (&mutex);/*Enter the critical section*/  theState[i] =thinking;/*The philosopher is finished eating*/  *Test (left);/*test whether their neighbourhood can eat*/  $Test (right);/*test whether the right neighbor can eat*/ Panax NotoginsengUp (&mutex);/*leave the critical section*/  - }  the  + voidTest (i)
 A {  the     if(State[i] ==hungry && state[left]! = EATING && state[right]! =EATING) {  +State[i] =EATING; -Up (&S[i]);  $     } $}

A philosopher is allowed to enter the dining state only when two neighbors are not eating!

The question of the Philosopher's meal