// C++ program to illustrate Banker's Algorithm
#include<iostream>
using namespace std;
// Number of processes
const int P = 5;
// Number of resources
const int R = 3;
// Function to find the need of each process
void calculateNeed(int need[P][R], int maxm[P][R],
int allot[P][R])
{
// Calculating Need of each P
for (int i = 0 ; i < P ; i++)
for (int j = 0 ; j < R ; j++)
// Need of instance = maxm instance -
// allocated instance
need[i][j] = maxm[i][j] - allot[i][j];
}
// Function to find the system is in safe state or not
bool isSafe(int processes[], int avail[], int maxm[][R],
int allot[][R])
{
int need[P][R];
// Function to calculate need matrix
calculateNeed(need, maxm, allot);
// Mark all processes as infinish
bool finish[P] = {0};
// To store safe sequence
int safeSeq[P];
// Make a copy of available resources
int work[R];
for (int i = 0; i < R ; i++)
work[i] = avail[i];
// While all processes are not finished
// or system is not in safe state.
int count = 0;
while (count < P)
{
// Find a process which is not finish and
// whose needs can be satisfied with current
// work[] resources.
bool found = false;
for (int p = 0; p < P; p++)
{
// First check if a process is finished,
// if no, go for next condition
if (finish[p] == 0)
{
// Check if for all resources of
// current P need is less
// than work
int j;
for (j = 0; j < R; j++)
if (need[p][j] > work[j])
break;
// If all needs of p were satisfied.
if (j == R)
{
// Add the allocated resources of
// current P to the available/work
// resources i.e.free the resources
for (int k = 0 ; k < R ; k++)
work[k] += allot[p][k];
// Add this process to safe sequence.
safeSeq[count++] = p;
// Mark this p as finished
finish[p] = 1;
found = true;
}
}
}
// If we could not find a next process in safe
// sequence.
if (found == false)
{
cout << "System is not in safe state";
return false;
}
}
// If system is in safe state then
// safe sequence will be as below
cout << "System is in safe state.\nSafe"
" sequence is: ";
for (int i = 0; i < P ; i++)
cout << safeSeq[i] << " ";
return true;
}
// Driver code
int main()
{
int processes[] = {0, 1, 2, 3, 4};
// Available instances of resources
int avail[] = {3, 3, 2};
// Maximum R that can be allocated
// to processes
int maxm[][R] = {{7, 5, 3},
{3, 2, 2},
{9, 0, 2},
{2, 2, 2},
{4, 3, 3}};
// Resources allocated to processes
int allot[][R] = {{0, 1, 0},
{2, 0, 0},
{3, 0, 2},
{2, 1, 1},
{0, 0, 2}};
// Check system is in safe state or not
isSafe(processes, avail, maxm, allot);
return 0;
}
You could have a look at:
Or if you had searched our forum:
And so you have a good start with a buggy script, now all you have to do is debug!
Good luck!
We are here to assist you, not to do your work!
If you go in to debug the above script, we may assist you when you are stuck, if you are able to describe your issue and not just say like the previous you are stuck... and the deal of course will be to publish all the hard process of getting things to work, and publishing here the final result: a complet working script
Less than that, I doubt you find much help as there are plenty resource on the subject on the net, it is only a question of doing one's own share of required work you were asked to do...
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Thank you for your constructive criticism, sir.
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