Shortest Job First SJF Scheduling Algorithm in C and C++ with Gantt Chart

Shortest Job First SJF Scheduling Algorithm in C and C++ with Gantt Chart .

C++ Program Code:

#include <bits/stdc++.h>
using namespace std;

const int N=100005;

int n;
struct process
{
    int id;
    int burst_time;
    int arrival_time;
    int waiting_time;
    int finishing_time;
    int turn_around_time;
};
process P[N];

void SJF()
{
    int complete,current_time,index,minimum;
    double total_waiting_time = 0.0;
    double total_turn_around_time = 0.0;

    index = -1;
    complete = 0;
    current_time = 0;
    minimum = INT_MAX;

    while(complete < n)
    {
        for(int i=0; i<n; i++)
        {
            if(P[i].arrival_time <= current_time)
            {
                if(P[i].burst_time < minimum && P[i].finishing_time == 0)
                {
                    index = i;
                    minimum = P[i].burst_time;
                }
            }
        }

        if(index >= 0)
        {
            complete++;
            minimum = INT_MAX;
            current_time += P[index].burst_time;
            P[index].finishing_time = current_time;
            P[index].turn_around_time = P[index].finishing_time - P[index].arrival_time;
            P[index].waiting_time =  P[index].turn_around_time- P[index].burst_time;

            total_waiting_time += P[index].waiting_time;
            total_turn_around_time += P[index].turn_around_time;

            index = -1;
        }
        else
        {
            current_time++;
        }
    }

    cout<<fixed<<setprecision(2);
    cout<<"Average Waiting Time: "<<(total_waiting_time/n)<<"\n";
    cout<<"Average Turn Around Time: "<<(total_turn_around_time/n)<<"\n";
}

int main()
{
    cout<<"Number of Processes: ";
    cin>>n;

    cout<<"Process Ids:\n";
    for(int i=0; i<n; i++) cin>>P[i].id;

    cout<<"Process Burst Times:\n";
    for(int i=0; i<n; i++) cin>>P[i].burst_time;

    cout<<"Process Arrival Times:\n";
    for(int i=0; i<n; i++) cin>>P[i].arrival_time;

    SJF();

    return 0;
}
/**
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*/

#include <bits/stdc++.h>

using namespace std;

const int N=100005;

int n;

struct process

{

int id;

int burst_time;

int arrival_time;

int waiting_time;

int finishing_time;

int turn_around_time;

};

process P[N];

void SJF()

{

int complete,current_time,index,minimum;

double total_waiting_time = 0.0;

double total_turn_around_time = 0.0;

index = -1;

complete = 0;

current_time = 0;

minimum = INT_MAX;

while(complete < n)

{

for(int i=0; i<n; i++)

{

if(P[i].arrival_time <= current_time)

{

if(P[i].burst_time < minimum && P[i].finishing_time == 0)

{

index = i;

minimum = P[i].burst_time;

}

if(index >= 0)

{

complete++;

minimum = INT_MAX;

current_time += P[index].burst_time;

P[index].finishing_time = current_time;

P[index].turn_around_time = P[index].finishing_time - P[index].arrival_time;

P[index].waiting_time = P[index].turn_around_time- P[index].burst_time;

total_waiting_time += P[index].waiting_time;

total_turn_around_time += P[index].turn_around_time;

index = -1;

}

else

{

current_time++;

}

cout<<fixed<<setprecision(2);

cout<<"Average Waiting Time: "<<(total_waiting_time/n)<<"\n";

cout<<"Average Turn Around Time: "<<(total_turn_around_time/n)<<"\n";

}

int main()

{

cout<<"Number of Processes: ";

cin>>n;

cout<<"Process Ids:\n";

for(int i=0; i<n; i++) cin>>P[i].id;

cout<<"Process Burst Times:\n";

for(int i=0; i<n; i++) cin>>P[i].burst_time;

cout<<"Process Arrival Times:\n";

for(int i=0; i<n; i++) cin>>P[i].arrival_time;

SJF();

return 0;

}

/**

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C Program Code:

#include <stdio.h>
#include <stdlib.h>

#define MAX_PROCESS 100

struct process {
    int pid;
    int burst_time;
    int waiting_time;
};

typedef struct process Process;


double average_waiting_time;
int total_waiting_time;

void sort_process_by_burst_time(Process p[], int n);
void calculate_waiting_time(Process p[], int n);
void print_gantt_chart(Process p[], int n);

int main()
{
    Process p[MAX_PROCESS];
    int n, i, j;
    puts("SHORTEST JOB FIRST SCHEDULING ALGORITHM");
    puts("=======================================");

    printf("Enter total process: ");
    scanf("%d", &n);
    printf("Enter burst time for each process:\n");
    for(i=0; i<n; i++) {
        printf("P[%d]: ", i+1);
        scanf("%d", &p[i].burst_time);
        p[i].pid = i+1;
    }

    sort_process_by_burst_time(p, n);
    calculate_waiting_time(p, n);

    average_waiting_time = (double) ( (double)total_waiting_time / (double) n );

    puts("");
    printf("Average Waiting Time: %.2lf\n",average_waiting_time);

    printf("Gantt Chart:\n");
    print_gantt_chart(p, n);


    return 0;
}

void sort_process_by_burst_time(Process p[], int n)
{
    int i, j;
    Process temp;
    for(i=0; i<n-1; i++) {
        for(j=0; j<n-1-i; j++) {
            if(p[j].burst_time > p[j+1].burst_time) {
                temp = p[j];
                p[j] = p[j+1];
                p[j+1] = temp;
            }
        }
    }
}

void calculate_waiting_time(Process p[], int n)
{
    int i;
    total_waiting_time = 0;
    p[0].waiting_time = 0;
    for(i=1; i<n; i++) {
        p[i].waiting_time = p[i-1].waiting_time + p[i-1].burst_time;
        total_waiting_time += p[i].waiting_time;
    }
}

void print_gantt_chart(Process p[], int n)
{
    int i, j;
    int last = p[n-1].burst_time + ( n== 1 ? 0 : p[n-1].waiting_time);
    // printing top bar
    printf(" ");
    for(i=0; i<n; i++) {
        for(j=0; j<p[i].burst_time; j++) printf("--");
        printf(" ");
    }
    printf("\n|");
    // middle position
    for(i=0; i<n; i++) {
        for(j=0; j<p[i].burst_time-1; j++) printf(" ");
        printf("p%d", p[i].pid);
        for(j=0; j<p[i].burst_time-1; j++) printf(" ");
        printf("|");
    }
    printf("\n ");
    // bottom bar
    for(i=0; i<n; i++) {
        for(j=0; j<p[i].burst_time; j++) printf("--");
        printf(" ");
    }
    printf("\n");

    // printing waiting time
    int minus = 0;
    for(i=0; i<n; i++) {
        if(p[i].waiting_time>9) printf(" ");
        printf("%d", p[i].waiting_time);
        if(p[i+1].waiting_time>9){
          minus = 1;
        }
        if(i+1 == n )  if (last>9) minus = 1;
        for(j=0; j<p[i].burst_time-minus; j++) printf("  ");

    }
    if(last>9) printf(" ");
    printf("%d\n", last);
}

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#include <stdio.h>

#include <stdlib.h>

#define MAX_PROCESS 100

struct process {

int pid;

int burst_time;

int waiting_time;

};

typedef struct process Process;

double average_waiting_time;

int total_waiting_time;

void sort_process_by_burst_time(Process p[], int n);

void calculate_waiting_time(Process p[], int n);

void print_gantt_chart(Process p[], int n);

int main()

{

Process p[MAX_PROCESS];

int n, i, j;

puts("SHORTEST JOB FIRST SCHEDULING ALGORITHM");

puts("=======================================");

printf("Enter total process: ");

scanf("%d", &n);

printf("Enter burst time for each process:\n");

for(i=0; i<n; i++) {

printf("P[%d]: ", i+1);

scanf("%d", &p[i].burst_time);

p[i].pid = i+1;

}

sort_process_by_burst_time(p, n);

calculate_waiting_time(p, n);

average_waiting_time = (double) ( (double)total_waiting_time / (double) n );

puts("");

printf("Average Waiting Time: %.2lf\n",average_waiting_time);

printf("Gantt Chart:\n");

print_gantt_chart(p, n);

return 0;

}

void sort_process_by_burst_time(Process p[], int n)

{

int i, j;

Process temp;

for(i=0; i<n-1; i++) {

for(j=0; j<n-1-i; j++) {

if(p[j].burst_time > p[j+1].burst_time) {

temp = p[j];

p[j] = p[j+1];

p[j+1] = temp;

}

void calculate_waiting_time(Process p[], int n)

{

int i;

total_waiting_time = 0;

p[0].waiting_time = 0;

for(i=1; i<n; i++) {

p[i].waiting_time = p[i-1].waiting_time + p[i-1].burst_time;

total_waiting_time += p[i].waiting_time;

}

void print_gantt_chart(Process p[], int n)

{

int i, j;

int last = p[n-1].burst_time + ( n== 1 ? 0 : p[n-1].waiting_time);

// printing top bar

printf(" ");

for(i=0; i<n; i++) {

for(j=0; j<p[i].burst_time; j++) printf("--");

printf(" ");

}

printf("\n|");

// middle position

for(i=0; i<n; i++) {

for(j=0; j<p[i].burst_time-1; j++) printf(" ");

printf("p%d", p[i].pid);

for(j=0; j<p[i].burst_time-1; j++) printf(" ");

printf("|");

}

printf("\n ");

// bottom bar

for(i=0; i<n; i++) {

for(j=0; j<p[i].burst_time; j++) printf("--");

printf(" ");

}

printf("\n");

// printing waiting time

int minus = 0;

for(i=0; i<n; i++) {

if(p[i].waiting_time>9) printf(" ");

printf("%d", p[i].waiting_time);

if(p[i+1].waiting_time>9){

minus = 1;

}

if(i+1 == n ) if (last>9) minus = 1;

for(j=0; j<p[i].burst_time-minus; j++) printf(" ");

}

if(last>9) printf(" ");

printf("%d\n", last);

}

Output and Gantt Chart:

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Shortest Job First SJF Scheduling Algorithm in C and C++ with Gantt Chart

Shortest Job First SJF Scheduling Algorithm in C and C++ with Gantt Chart .

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