Wednesday 16 January 2019

Essential Shell Commands

Sunday 9 April 2017

How to increase Virtual Box Hard Disk Size

Here is what I've fixed the issue. 

Initially I created Virtual Box of 15GB of space. 

When I run into out-of-space issue. I did following. 

Two steps involved to resize existing virtual disk space. 

1) Using VBoxManage utility tool provided by Oracle VirtualBox ;  Allocate enough space based on requirement. In my case I've increased from 15GB to 25GB. 

I did this; 

Checked if this present ; 

"C:\Program Files\Oracle\VirtualBox\VBoxManage"

Then Run- CMD , to set environment variable
set PATH=%PATH%;C:\Program Files\Oracle\VirtualBox
Go to path where you have installed VirtualBox. My case
C:\Users\ssankar\VirtualBox VMs\ssankar-ubuntu>VBoxManage modifyhd ssankar-ubuntu.vdi --resize 25000
0%...10%...20%...30%...40%...50%...60%...70%...80%...90%...100%

C:\Users\ssuriyanarayanan\VirtualBox VMs\ssankar-ubuntu>

Done Now If you open VirtualBox you will able to see "Virtual Box Size: 25GB " . Actual Size "14 GB". 

Step:2: Now create partition from un-allocated space of 10GB. This can be achieved using tool call Gparted

For this step I've followed : http://derekmolloy.ie/resize-a-virtualbox-disk/#prettyPhoto


Tuesday 14 June 2016

Reverse Linked List

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

struct node {
        int             data;
        struct node *next;
};

void AppendToList (struct node **head, int value)
{
        struct node *newNode = NULL;

        newNode = (struct node *) malloc(sizeof(struct node));
        if (newNode == NULL)
                return;

        newNode->data = value;
        newNode->next = NULL;

        if (*head == NULL)
                        *head = newNode;
        else {
                newNode->next = *head;
                *head   = newNode;
        }

        return;
}

void PrintList (struct node **head)
{
        struct node *temp = *head;

        while (temp) {
                printf("%d\r\n", temp->data);
                temp = temp->next;
        }

        return;
}

void ReverseList (struct node **head)
{
        struct node *prev = NULL, *curr = *head, *next = NULL;

        while (curr != NULL) {
                        next = curr->next;
                        curr->next = prev;
                        prev = curr;
                        curr = next;
        }
        *head = prev;

        return;
}

int main(void)
{
        int i;
        struct node *head = NULL;

        for (i = 1; i <= 10; i++) {
                AppendToList(&head, i);
        }

        printf("List \r\n");
        PrintList(&head);

        ReverseList(&head);
        printf("Reversed List\r\n");
        PrintList(&head);

        return 0;
}

CC = gcc

CFLAGS = -g -Wall

all: reverselist

reverselist: reverselist.o
        ${CC} ${CLAGS} -o $@ reverselist.o

clean:
        -@rm *.o

Swap linked list node without swapping data

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

struct node {
        int             data;
        struct node *next;
};

void AppendToList (struct node **head, int value)
{
        struct node *newNode = NULL;

        newNode = (struct node *) malloc(sizeof(struct node));
        if (newNode == NULL)
                return;

        newNode->data = value;
        newNode->next = NULL;

        if (*head == NULL)
                        *head = newNode;
        else {
                newNode->next = *head;
                *head   = newNode;
        }

        return;
}

void PrintList (struct node **head)
{
        struct node *temp = *head;

        while (temp) {
                printf("%d\r\n", temp->data);
                temp = temp->next;
        }

        return;
}

void swapNodes (struct node **head, int a, int b)
{
        struct node *prev_x, *curr_x;
        struct node *prev_y, *curr_y, *temp;

        curr_x = *head;
        while (curr_x && (curr_x->data != a)) {
                prev_x = curr_x;
                curr_x = curr_x->next;
        }

        curr_y = *head;
        while (curr_y && (curr_y->data != b)) {
                prev_y = curr_y;
                curr_y = curr_y->next;
        }

        prev_x->next = curr_y;
        temp                             = curr_y->next;
        curr_y->next = curr_x->next;

        prev_y->next = curr_x;
        curr_x->next = temp;

        return;
}


int main(int argc, char *argv[])
{
        int i;
        struct node *head = NULL;

        if (argc <= 2) {
                printf("usage: ./swapnode <a> <b> \r\n");
                return 0;
        }

        for (i = 1; i <= 10; i++) {
                AppendToList(&head, i);
        }

        printf("List\r\n");
        PrintList(&head);

        swapNodes(&head, atoi(argv[1]), atoi(argv[2]));
        printf("After swap\r\n");
        PrintList(&head);

        return 0;
}



CC = gcc

CFLAGS = -g -Wall

all : swapnode
swapnode: swapnode.o
        ${CC} ${CFLAGS} -o $@ swapnode.o

clean:
        -@rm *.o

Wednesday 8 June 2016

Linked List FIFO

FIFO List

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

struct node {
        int             data;
        struct node *next;
};

void InsertToFIFO (struct node **head, struct node **tail, int value)
{
        struct node *newNode = NULL;

        newNode = (struct node *) malloc(sizeof(struct node));
        if (newNode == NULL)
                return;

        newNode->data = value;
        newNode->next = NULL;

        if (*head == NULL) {
                        *head = newNode;
                        *tail = newNode;
        } else {
                        (*tail)->next = newNode;
                        *tail   = newNode;
        }

        return;
}

void PrintList (struct node **head)
{
        struct node *temp = *head;

        while (temp) {
                printf("%d\r\n", temp->data);
                temp = temp->next;
        }

        return;
}

int main(void)
{
        int i;
        struct node *head = NULL, *tail = NULL;

        for (i = 1; i <= 10; i++) {
                InsertToFIFO(&head, &tail, i);
        }
        printf("FIFO List \r\n");
        PrintList(&head);

        return 0;
}

Makefile:
CC = gcc

CFLAGS = -g -Wall

all:  queue_list
queue_list: queue_list.o
        ${CC} ${CFLAGS} -o $@ queue_list.o

clean:
        -@rm *.o

distclean: clean
         -@rm    queue_list

Output:
FIFO List
1
2
3
4
5
6
7
8
9
10

Find the middle node in the linked list

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

struct node {
        int             data;
        struct node *next;
};

void AppendToList (struct node **head, int value)
{
        struct node *newNode = NULL;

        newNode = (struct node *) malloc(sizeof(struct node));
        if (newNode == NULL)
                return;

        newNode->data = value;
        newNode->next = NULL;

        if (*head == NULL)
                        *head = newNode;
        else {
                newNode->next = *head;
                *head   = newNode;
        }

        return;
}

void PrintList (struct node **head)
{
        struct node *temp = *head;

        while (temp) {
                printf("%d\r\n", temp->data);
                temp = temp->next;
        }

        return;
}

/* traverse double the time
 * return the first pointer
 * basically divide by 2 algorithm
 * **/
void FindMiddleNode (struct node **head, struct node **middle)
{
        struct node *temp1, *temp2;

        temp1 = temp2 = *head;

        while (temp2 != NULL) {
                temp1 = temp1->next;
                temp2 = temp2->next->next;
        }
        *middle = temp1;

        return;
}

int main(void)
{
        int i;
        struct node *head = NULL;
        struct node *middle = NULL;

        for (i = 1; i <= 10; i++) {
                AppendToList(&head, i);
        }

        printf("List \r\n");
        PrintList(&head);

        FindMiddleNode(&head, &middle);
        printf("Middle Node %d \r\n", middle->data);

        return 0;
}



Makefile: 


CC = gcc

CFLAGS = -g -Wall

all: mergenode findAndRemoveLoop middlenode

mergenode: mergenode.o
        ${CC} ${CFLAGS} -o $@ mergenode.o

findAndRemoveLoop: findAndRemoveLoop.o
        ${CC} ${CFLAGS} -o $@ findAndRemoveLoop.o

middlenode: middlenode.o
        ${CC} ${CFLAGS} -o $@ middlenode.o

clean:
        -@rm *.o

distclean: clean
        -@rm    mergenode
        -@rm    findAndRemoveLoop
        -@rm    middlenode


Output: 

List
10
9
8
7
6
5
4
3
2
1
Middle Node 5

Find loop in the list and remove it

Following program to find the loop in the list and correct the loop


- Algorithm :  loop through the list and return any node from the list

- Remove the loop :
                    Traverse the head and check if the looped node matches


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

struct node {
        int             data;
        struct node *next;
};

void AppendToList (struct node **head, int value)
{
        struct node *newNode = NULL;

        newNode = (struct node *) malloc(sizeof(struct node));
        if (newNode == NULL)
                return;

        newNode->data = value;
        newNode->next = NULL;

        if (*head == NULL)
                        *head = newNode;
        else {
                newNode->next = *head;
                *head   = newNode;
        }

        return;
}

void PrintList (struct node **head)
{
        struct node *temp = *head;

        while (temp) {
                printf("%d\r\n", temp->data);
                temp = temp->next;
        }

        return;
}

void CreateLoopedList (struct node **head)
{
        struct node *temp = *head;
        struct node *merge = *head;

        while (temp->next != NULL) {
                temp = temp->next;
        }
        printf ("Created Loop Between Node\r\n == %d -> %d == \r\n", temp->data, (merge->next->next->next)->data);
        temp->next = merge->next->next->next;

        return;
}

void FindLoopInList (struct node **head, struct node **loopNode)
{
        struct node *slow = NULL, *fast = NULL;

        slow = fast = *head;

        /* alternatively use visit flag
         * to find loop node
         * */
        while (slow && fast) {
                slow = slow->next;
                fast = fast->next->next;
                if (slow == fast) {
                        /* return any node in the loop
                         * where slow and fast ptr are met
                         **/
                        *loopNode = slow;
                        break;
                }
        }

        return;
}

void RemoveLoopFromList (struct node **head, struct node *loopNode)
{
        struct node *temp1 = *head;
        struct node *temp2 = NULL;

        while (*head) {
                        temp2 = loopNode;
                        /* start from head move temp1 for each looped node not found case
                         * keep move temp2 , unless looping node found
                         * temp1 traverse from head
                         * temp2 loop from looped one side node
                         * any point of time temp1 == temp2 then break
                         * **/
                        while (temp2->next != loopNode && temp2->next != temp1) {
                                                temp2 = temp2->next;
                        }

                        if (temp2->next == temp1) {
                                                /* found the loop, make next to null
                                                **/
                                                temp2->next = NULL;
                                                return;
                        }

                        temp1 = temp1->next;
        }

        return;
}

int main(void)
{
        int i;
        struct node *head = NULL;
        struct node *loopNode = NULL;

        for (i = 1; i <= 10; i++) {
                AppendToList(&head, i);
        }
        printf("Head List \r\n");
        PrintList(&head);

        CreateLoopedList(&head);
        FindLoopInList(&head, &loopNode);

        RemoveLoopFromList(&head, loopNode);

        printf("After removing looped List \r\n");
        PrintList(&head);

        return 0;
}

Makefile:

CC = gcc

CFLAGS = -g -Wall

all: mergenode findAndRemoveLoop

mergenode: mergenode.o
        ${CC} ${CFLAGS} -o $@ mergenode.o

findAndRemoveLoop: findAndRemoveLoop.o
        ${CC} ${CFLAGS} -o $@ findAndRemoveLoop.o

clean:
        -@rm *.o

distclean: clean
        -@rm    mergenode
        -@rm    findAndRemoveLoop


Output: 

Head List
10
9
8
7
6
5
4
3
2
1
Created Loop Between Node
 == 1 -> 7 ==
After removing looped List
10
9
8
7
6
5
4
3
2
1