Banker's algorithm

Problem No: 12

Name of the problem: Banker’s algorithm

Theory: The banker’s algorithm is a resource allocation and deadlock avoidance algorithm that tests for safety by simulating the allocation for predetermined maximum possible amounts of all resources then make an “s-state” check to test for possible activities, before deciding whether allocation should be allowed to continue.

Code:

#include<bits/stdc++.h>

using namespace std;

#include<string.h>

int main()

{

 int n,m,i,j,k,f=0,ar[10],z=0;//n=no_of_process,m=no_of_resources

    printf("Enter the number of processes   -");

    scanf("%d",&n);

    int finished[n];

    memset(finished+0,0,n*sizeof(int));

    printf("Enter the number of resources   -");

    scanf("%d",&m);

    int allocation[n][m],need[n][m],max[n][m],available[m],request[m];

    for(i=0; i<n; i++)

    { printf("Enter details for P%d\nEnter allocation\t\t-",i);

        for(j=0; j<m; j++)

        {scanf("%d",&allocation[i][j]);

        }

        printf("Enter max\t\t\t-");

        for(j=0; j<m; j++)

        {

            scanf("%d",&max[i][j]);

            need[i][j]=max[i][j]-allocation[i][j];

        }

}

    printf("Enter Available Resources\t-");

    for(i=0; i<m; i++)

        scanf("%d",&available[i]);

    printf("Enter new request details--\nEnter pid\t\t\t");

    int temp;

    scanf("%d",&temp);

    printf("Enter new request details\t-");

    for(i=0; i<m; i++)

    {scanf("%d",&request[i]);

        available[i]=available[i]-request[i];

        allocation[temp][i]= allocation[temp][i]+request[i];

        need[temp][i]=max[temp][i]-allocation[temp][i];

    }

    cout<<"----------------OUTPUT-----------------"<<endl<<endl;

    int loop=n;

    while(loop--)

    {for(i=0; i<n; i++)

        {if(finished[i]==0)

            {

                k=0;

                for(j=0; j<m; j++)

                {

                    if(need[i][j]<=available[j])

                        k++;

                    else

                        break;

                }

                if(k==m)

                {

                    finished[i]=1;

                    f++;

                    printf("\nP%d is visited ",i);

                    ar[z++]=i;

                    for(j=0; j<m; j++)

                    {

                        available[j]=allocation[i][j]+available[j];

                        printf("%d ",available[j]);

                    }}}}

        if(f==n)

        {break; }

}

    cout<<"System in safe state"<<endl<<"Safe sequence--( ";

    for(i=0; i<z; i++)

    {

        cout<<"P"<<ar[i]<<" ";

    }

    cout<<" )";

    printf("\n");

    for(i=0; i<n; i++)

    {

        printf("\nP%d\t",i);

        for(k=0; k<m; k++)

            printf("%d ",allocation[i][k]);

        printf("\t");

        for(k=0; k<m; k++)

            printf("%d ",max[i][k]);

        printf("\t");

        for(k=0; k<m; k++)

            printf("%d ",need[i][k]);

    }}