Saturday, 23 June 2012

c++ program of preemitive prority based scheduling algorithm.

#include <iostream>
using namespace std;
int main()
{    int n;
    cout<<"enter your toal no. of process";
    cin>>n;
    float total,wait[n];
    float p[n],twaiting=0,waiting=0;
    int proc;
    int stack[n];
    float brust[n],arrival[n],sbrust,temp[n],top=n,prority[n];
    int i;
   


for(i=0;i<n;i++)
    {
        p[i]=i;
        stack[i]=i;
        cout<<"enter arival time :";
        cin>>arrival[i];
        cout<<endl<<"enter brust time:";
        cin>>brust[i];
        cout<<endl<<"enter prority time:";
        cin>>prority[i];
        temp[i]=arrival[i];
        sbrust=brust[i]+sbrust;
     }

    for(i=0;i<sbrust;i++)
    {   
        //section 1
        proc=stack[0];
        if(temp[proc]==i)
                    twaiting=0;
       else
                  twaiting=i-(temp[proc]);
           temp[proc]=i+1;   
           wait[proc]=wait[proc]+twaiting;
            waiting=waiting+(twaiting);
            brust[proc]=brust[proc]-1;
                          
        if(brust[proc]==0)
        {
            for(int x=0;x<top-1;x++)
                        stack[x]=stack[x+1];
              top=top-1;
         }
        for(int z=0;z<top-1;z++)
        {  
            if((prority[stack[0]]>prority[stack[z+1]]) && (arrival[stack[z+1]] <= i+1))
            {
                   int t=stack[0];
                   stack[0]=stack[z+1];
                  stack[z+1]=t;
            }        
         }
      }
cout<<"Average waiting time is:"<<waiting/n;
float tu=(sbrust+waiting)/n;
cout<<endl<<"Average turnaround time is:"<<tu;
return 0;
}



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