Wednesday, June 15, 2016

Search a Tree - C program

Computer is a robot , our program  should identify the repetitive task and make computer do that repetitive task with less lines of code.... programmer should be able to identify the repetitive task and apply recursive functions..

Search a value in a Tree - C program

the beauty of this code is that searching the tree (function:searchtree ) is going to be the one function.But we will make the computer to do the same task repetitively just passing the next node.


#include
#include


struct node {
    int a;
    struct node* left;
    struct node* right;
};

struct node* insert_node(int a){

    struct node* newnode;
    newnode = (struct node*) malloc (sizeof(struct node));
    newnode->a = a;
    newnode->left = NULL;
    newnode->right = NULL;

    return newnode;
}

int searchtree(struct node* root,int num){
    if(root == NULL)
        return 0;
    if(root->a == num ||searchtree(root->left,num))
        return 1;
    if(root->a == num || searchtree(root->right,num)){       
        return 1;
    }   
   
}

       
   
           

int main(){

    int num;
    struct node* root;
   
    root = insert_node(1);
    root->left = insert_node(2);
    root->right = insert_node(3);
    root->right->right = insert_node(4);   
    root->right->left = insert_node(5);   
    root->left->left = insert_node(6);
    root->left->right = insert_node(7);
    root->left->right->left = insert_node(8);

    printf("type a number:");
    scanf("%d",&num);

    if(searchtree(root,num)){
        printf("number found in tree");
    }
    else{
        printf("number not found in tree");
    };
    return(0);
}

Tuesday, June 14, 2016

Python linked list

If you are planning to refresh your data structure knowledge, I would recommend this website http://www.geeksforgeeks.org/data-structures/

Tree or Linked list datastructure  programming heavily use the recursion concept ... recursion is something that sometimes cause me brain crash :-)

But once you understand it and learn how to use recursion , then that is where you start mastering datastructure concepts.

If you look at Tree or linked list, it is a repetition of a node or a same structure(http://quiz.geeksforgeeks.org/binary-tree-set-1-introduction/)   .. so when there is repetition of something, then there is always scope for recursion concepts to apply...

Python Linked List:

Python programming language also have OOP concepts. So that means we can define a class http://www.diveintopython.net/object_oriented_framework/defining_classes.html

You can go through the linked list details in the below link
http://quiz.geeksforgeeks.org/linked-list-set-1-introduction/ . You will see two classes they defined for implementing linked list.

I was just trying to build without 2 classes. We can build a linked list, I dont know why they used 2 classes..I am not sure on how python is doing this dynamic memory allocation.



Program:



Strace:


Monday, June 13, 2016

Strace on a tree structure C program

When I tried to access 'unallocated node value' , as usual 'Segmentation fault' came as output :-)

But i am not fully clear on how mmap() system call allocate the memory...

I also came to know that mprotect() system call sets the protection,

If the calling process tries to access memory in a manner that violates the protection, then the kernel generates a SIGSEGV signal for the process.

Program and Strace details: