OS- First Come First Serve - FCFS Scheduling

 #include <stdio.h>

int main()

{

    int pid[15];

    int bt[15];

    int n,i;

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

    scanf("%d",&n);

 

    printf("Enter process id of all the processes: ");

    for(i=0;i<n;i++)

    {

        scanf("%d",&pid[i]);

    }

 

    printf("Enter burst time of all the processes: ");

    for( i=0;i<n;i++)

    {

        scanf("%d",&bt[i]);

    }

 

    int wt[n];

    wt[0]=0;

 

    //for calculating waiting time of each process

    for(i=1; i<n; i++)

    {

        wt[i]= bt[i-1]+ wt[i-1];

    }

 

    printf("Process ID     Burst Time     Waiting Time     TurnAround Time\n");

    float twt=0.0;

    float tat= 0.0;

    for(i=0; i<n; i++)

    {

        printf("%d\t\t", pid[i]);

        printf("%d\t\t", bt[i]);

        printf("%d\t\t", wt[i]);

 

        //calculating and printing turnaround time of each process

        printf("%d\t\t", bt[i]+wt[i]);

        printf("\n");

 

        //for calculating total waiting time

        twt += wt[i];

 

        //for calculating total turnaround time

        tat += (wt[i]+bt[i]);

    }

    float att,awt;

 

    //for calculating average waiting time

    awt = twt/n;

 

    //for calculating average turnaround time

    att = tat/n;

    printf("Avg. waiting time= %f\n",awt);

    printf("Avg. turnaround time= %f",att);

}

Program run command in Linux(Ubuntu)

 For Cpp

Create- gedit filename.cpp

Compile- g++ filename.cpp

Run- ./a.out

For C

Create- gedit filename.c

Compile- gcc filename.c

Run- ./a.out

For Java

Create- gedit filename.java

Compile- javac filename.java

Run- java filename

For python

Create- gedit filename.py

python3 filename.py  //only interpreter is used in python

Infix to prefix conversion

 ALGORITHM:

STEP 1:

Add " ( " at the beginning of the infix expression and then reverse.

STEP 2:

Push " ) " on to the stack.

STEP 3:

Scan every character and repeat step 4 to step 7 until " ( " is encountered.

STEP 4:

If input is operand add in the output.

STEP 5:

If input is " ) " push into the stack.

STEP 6:

If input is "(" pop all the operators from the stack and add in the output one by one until ")" is popped.

STEP 7:

If input is operator pop all the stack which is higher precedence than input operator .Push input operator into the stack.

STEP 8:

Reverse the output

EXAMPLE:

Infix to postfix conversion

 Step 1: Add " ) " to the end of the infix expression 

Step 2: Push " ( " on to the stack 

Step 3: Repeat until each character in the infix notation is scanned 

            - IF a " ( " is encountered, push it on the stack IF an operand (whether a digit or a character) is                      encountered, add it postfix expression. 

            - IF a " ) " is encountered, then 

                       a. Repeatedly pop from stack and add it to the postfix expression until a " ( " is                                             encountered. 

                       b. Discard the " ( " . That is, remove the " ( " from stack and do not add it to the postfix                              expression. 

           - IF an operator is encountered, then 

                      a. Repeatedly pop from stack and add each operator (popped from the stack) to the postfix expression which has the same precedence or a higher precedence than  0 .

                      b. Push the operator to the stack [END OF IF] 

Step 4: Repeatedly pop from the stack and add it to the postfix expression until the stack is empty 

Step 5: EXIT

Linked list push-pop

 #include<stdio.h>

#include<stdlib.h>

struct node {

    int data;

    struct node* link;

};

struct node* top = NULL;

void push() {

    struct node* temp = (struct node*) malloc(sizeof(struct node));

    printf("Enter a value: ");

    scanf("%d", &temp->data);

    temp->link = top;

    top = temp;

}

void pop() {

    if (top == NULL) {

        printf("Stack underflow\n");

    } else {

        struct node* temp = top;

        top = top->link;

        printf("Popped value = %d\n", temp->data);

        free(temp);

    }

}

void display() {

    if (top == NULL) {

        printf("Empty stack\n");

    } else {

        struct node* temp = top;

        while (temp != NULL) {

            printf("%d ", temp->data);

            temp = temp->link;

        }

        printf("\n");

    }

}

int main() {

    int choice;

    while (1) {

        printf("Enter 1 for push\n");

        printf("Enter 2 for pop\n");

        printf("Enter 3 for display\n");

        printf("Enter 4 for exit\n");

        printf("Enter your choice: ");

        scanf("%d", &choice);

        switch (choice) {

            case 1:

                push();

                break;

            case 2:

                pop();

                break;

            case 3:

                display();

                break;

            case 4:

                printf("Exiting the program\n");

                exit(0);

            default:

                printf("Wrong choice\n");

        }

    }

    return 0;

}

Array Insertion deletion

  #include<iostream>

using namespace std;

class array

{

int a[30], n;

public:

void input()

{

cout<<"Enter the length: ";

cin>>n;

cout<<"Enter a value for the array "<<endl;

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

cin>>a[i];

}

void insert_begin()

{

int value;

cout<<"Enter a value for insertion at the front "<<endl;

cin>>value;

n=n+1;

for(int i=n-1; i>=1; i--)

{

a[i]=a[i-1];

}

a[0]=value;

}

void insert_end()

{

int value;

cout<<"Enter a value for insertion at the end "<<endl;

cin>>value;

n=n+1;

a[n-1]=value;

}

void insert_position()

{

int pos;

cout<<"Enter the position "<<endl;

cin>>pos;

int value;

cout<<"Enter the value "<<endl;

cin>>value;

for(int i=n-1; i>=pos; i--)

{

a[i]=a[i-1];

}

a[pos-1]=value;

}

void display()

{

cout<<"The value of array "<<endl;

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

cout<<a[i]<<" ";

cout<<endl;

}

void delete_begin()

{

int value;

value=a[0];

cout<<"The deleted value is "<<value<<endl;

for(int i=1; i<=n-1; i++)

{

a[i-1]=a[i];

}

n=n-1;

}

void delete_end()

{

int value;

value=a[n-1];

cout<<"The deleted value is "<<value<<endl;

n=n-1;

}

void delete_position()

{

int value, pos;

cout<<"Enter position "<<endl;

cin>>pos;

value=a[pos-1];

cout<<"The deleted value is "<<value<<endl;

for(int i=pos; i<=n-1; i++)

{

a[i-1]=a[i];

}

n=n-1;

}

};

int main()

{

array ob;

ob.input();

while(1)

{

cout<<"Enter 1 for displaying array "<<endl;

cout<<"Enter 2 for inserting element at the front "<<endl;

cout<<"Enter 3 for inserting element at the end "<<endl;

cout<<"Enter 4 for inserting element at the given position "<<endl;

cout<<"Enter 5 for deleting element from the front "<<endl;

cout<<"Enter 6 for deleting element from the end "<<endl;

cout<<"Enter 7 for deleting element from a given position "<<endl;

cout<<"Enter 8 for exit "<<endl;

int choice;

cin>>choice;

switch(choice)

{

case 1: 

ob.display();

break;

case 2:

cout<<"\nValue before insertion\n";

ob.display();

ob.insert_begin();

cout<<"\nValue after insertion\n";

ob.display();

break;

case 3:

cout<<"\nValue before insertion\n";

ob.display();

ob.insert_end();

cout<<"\nValue after insertion\n";

ob.display();

break;

case 4:

cout<<"\nValue before insertion\n";

ob.display();

ob.insert_position();

cout<<"\nValue after insertion\n";

ob.display();

break;

case 5:

cout<<"\nValue before deletion\n";

ob.display();

ob.delete_begin();

cout<<"\nValue after deletion\n";

ob.display();

break;

case 6:

cout<<"\nValue before deletion\n";

ob.display();

ob.delete_end();

cout<<"\nValue after deletion\n";

ob.display();

break;

case 7:

cout<<"\nValue before deletion\n";

ob.display();

ob.delete_position();

cout<<"\nValue after deletion\n";

ob.display();

break;

case 8:

cout<<"Exit from program";

break;

default:

cout<<"Enter a valid choice\n";

}

if(choice==8)

break;

}

return 0;

}

 

Sparse Matrix

 #include<iostream>

using namespace std;

int main()

{

int a[10][10],row,col,count=0,i,j,k=1;

int s[10][3];

cout<<"total number of row";

cout<<"total number of column";

cin>>row;

cin>>col;

cout<<"enter value";

for(i=0;i<row;i++)

{

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

{

cin>>a[i][j];

}

}

cout<<"matrix element\n";

for(i=0;i<row;i++)

{

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

{

cout<<a[i][j]<<" ";

}

cout<<"\n";

}

//count total number of nonzero elements

for(i=0;i<row;i++)

{

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

{

if(a[i][j]!=0)

{

count++;

}

}

}

cout<<count;

s[0][0]=row;

s[0][1]=col;

s[0][2]=count;

for(i=0;i<row;i++)

{

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

{

if(a[i][j]!=0)

{

s[k][0]=i;

s[k][1]=j;

s[k][2]=a[i][j];

k++;

}

}

}

cout<<"\n output array \n";

for(i=0;i<count+1;i++)

{

for(j=0;j<3;j++)

{

  cout<<s[i][j]<<" ";

}

cout<<"\n";

}

}