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It is majorly related to how the compiler reads( or parses) the entire code and breaks it into a set of instructions(or statements), to which semicolon in C acts as a boundary between two sets of instructions.

Merge two sorted linked lists and return them as a sorted list. The list should be made by splicing TOGETHER the nodes of the first two lists.

Runtime Complexity Linear, O(m + n) where m and n are lengths of both linked lists. 

Memory Complexity Constant, O(1)

MAINTAIN a head and a tail pointer on the merged linked list. Then choose the head of the merged linked list by comparing the first node of both linked lists. For all subsequent nodes in both lists, you choose the smaller current node and link it to the tail of the merged list, moving the current pointer of that list one step forward.

You keep doing this while there are some remaining elements in both lists. If there are STILL some elements in only one of the lists, you link this remaining list to the tail of the merged list.

Initially, the merged linked list is NULL. Compare the value of the first two nodes and make the node with the smaller value the head node of the merged linked list. In this example, it is 4 from head1.

Since it’s the first and only node in the merged list, it will also be the tail. Then move head1 one step forward.

C is the foundational language from which practically all other languages are built. C is the programming language's base. For writing system applications, it is a very POPULAR and frequently used language. Even if new languages have surpassed it in popularity, it remains one of the most popular programming languages. The C questions LISTED here will aid you in interviews as well as improve your learning. I hope you found these to be helpful!

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• Difference Between C and C++
• Features of C Language
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Let's take an EXAMPLE of the following two linked lists which intersect at node c1.

Solution -

• Get count of the NODES in the first list, let count be c1.
• Get count of the nodes in the second list, let count be c2.
• Get the difference of counts d = abs(c1 – c2)
• Now traverse the bigger list from the first node till d nodes so that from here ONWARDS both the lists have an equal no of nodes
• Then we can traverse both the lists in parallel till we COME across a common node. (Note that getting a common node is done by comparing the address of the nodes)

Fibonacci sequence is characterized by the fact that every number after the first two is the sum of the two preceding ONES. For example, consider below sequence

0, 1, 1, 2, 3, 5, 8, 13, 21, 34, . .. and so on

Where in F{n} = F{n-1} + F{n-2} with base VALUES F(0) = 0 and <code>F(1) = 1

Below is NAIVE IMPLEMENTATION for finding the NTH member of the Fibonacci sequence

Given a string s containing just the characters '(', ')', '{', '}', '[' and ']', determine if the input string is valid.

An input string is valid if:

• Open brackets must be closed by the same type of brackets.
• Open brackets must be closed in the correct order.

Example 1:
 Input: s = "()"
 Output: true

Example 2:
 Input: s = "()[]{}"
 Output: true

Example 3:
 Input: s = "(]"
 Output: false

Below is the source code for C Program to Check for Balanced PARENTHESES using Stack which is successfully compiled and run on Windows System to produce desired output as shown below :

Assume that we have linked list 1 → 2 → 3 → Ø, we would like to change it to Ø ← 1 ← 2 ← 3.

While you travel the linked list, change the current node's next pointer to point to its previous element. reference to the previous nodes should be stored into a temp variable as shown so that we don’t lose track of the swapped node. You also need another pointer to STORE the next node before changing the reference. Also when we are done return the new head of the REVERSED list.

#include<stdio.h>INT MAIN(){ int x; PRINTF("Enter a number: "); scanf("%d", &x); (x&1)?printf("ODD"):printf("Even"); return 0;}

The bitwise and(&) operator can be used to quickly CHECK the number is odd or even.

#include<stdio.h>int main(){ int x; printf("Enter a number: "); scanf("%d",&AMP;x); printf("%d", x<<1); return 0;}

The left shift OPERATOR shifts all bits towards the left by a certain number of specified bits. The expression x<<1 always returns x*2. Note that the shift operator doesn’t work on floating-point values.

For multiple of x by 4, use x<<2. Similarly x<<3 MULTIPLY x by 8. For multiple of the number x by 2^n, use x<<n.

#include&LT;stdio.h>#include<stdlib.h>int main(){ int X, y; printf("Enter two number: "); scanf("%d %d",&x,&y); printf("%d", x+(~y)+1); return 0;}

The BITWISE COMPLEMENT OPERATOR is used in this program. The bitwise complement of number ~y=-(y+1). So, expression will become x+(-(y+1))+1=x-y-1+1=x-y

For the SUM of two numbers, we use the addition (+) operator. In these tricky C programs, we will write a C program to add two numbers without using the addition operator.

A dynamic data structure (DDS) refers to an organization or collection of data in memory that has the flexibility to grow or shrink in size, enabling a programmer to CONTROL EXACTLY how much memory is utilized. Dynamic data structures change in size by having unused memory allocated or de-allocated from the heap as NEEDED. 

Dynamic data structures play a key role in programming LANGUAGES like C, C++, and Java because they provide the programmer with the flexibility to adjust the memory CONSUMPTION of software programs.

The keyword “void” is a data type that literally represents no data at all. The most obvious USE of this is a FUNCTION that RETURNS nothing:

Here we’ve declared a function, and all functions have a return type. In this case, we’ve said the return type is “void”, and that means, “no data at all” is returned. 
The other use for the void keyword is a void pointer. A void pointer points to the memory location where the data type is undefined at the time of variable definition. EVEN you can define a function of return type void* or void pointer meaning “at compile time we don’t know what it will return” Let’s see an example of that.

Header Files in C

In C header files must have the extension as .h, which contains function definitions, data TYPE definitions, macro, ETC. The header is useful to import the above definitions to the source code USING the #include directive. For example, if your source code needs to take input from the user do some manipulation and print the OUTPUT on the terminal, it should have stdio.h file included as #include <stdio.h&GT;, with which we can take input using scanf() do some manipulation and print using printf().

Source Code and Object Code Difference

The difference between the Source Code and Object Code is that Source Code is a collection of computer instructions WRITTEN using a human-readable programming language while Object Code is a sequence of statements in machine language, and is the OUTPUT after the compiler or an assembler converts the Source Code.

The last POINT about Object Code is the way the changes are REFLECTED. When the Source Code is modified, each time the Source Code needs to be compiled to REFLECT the changes in the Object Code.

The differences between MACROS and functions can be EXPLAINED as follows:

To call a FUNCTION before the MAIN(), pragma startup directive should be used. E.g.-

The output of the above program will be -

This pragma directive, on the other hand, is compiler-dependent. This is not SUPPORTED by gcc. As a result, it will ignore the startup directive and produce no error. But the output, in that case, will be -

Single Linked List

CIRCULAR Linked List

Circular linked list is a variation of a linked list where the last node is pointing to the first node's information part. Therefore the last node does not point to null.

A very simple way to determine whether the linked list is circular or not

• Traverse the linked list
• Check if the node is pointing to the head.
• If yes then it is circular.

Let's look at the snippet where we code this algorithm.

It is majorly related to how the compiler reads( or parses) the entire code and breaks it into a set of instructions(or statements), to which semicolon in C acts as a boundary between TWO sets of instructions.

#INCLUDE<stdio.h>#include<conio.h>int sumOfDigits(int num) { STATIC int sum = 0; int rem; sum = sum + (num%10); rem = num/10; if(rem > 0) { sumOfDigits(rem); } return sum; }int main() { int j,num; printf("Please enter a number :"); scanf("%d",&num); printf("sum of digits of the number = %d ",sumOfDigits(num)); getch();}

#include<stdio.h>#include<conio.h>INT main() { int J,num; printf("Please ENTER a number :"); SCANF("%d",&num); while(num>0) { j=num%10; if( j!=0 && j!=1 ) { printf("num is not binary"); break; } num=num/10; if(num==0) { printf("num is binary"); } } getch();}

#include &LT;stdio.h>#include <conio.h>int reverse(int num);int ISPALINDROME(int num);int main(){ int num; printf("Enter a NUMBER: "); scanf("%d", &num);if(isPalindrome(num) == 1){ printf("the given number is a palindrome"); } else { printf("the given number is not a palindrome number"); } return 0;}int isPalindrome(int num){ if(num == reverse(num)) { return 1; } return 0;}int reverse(int num){int rem; static int SUM=0; if(num!=0){ rem=num%10; sum=sum*10+rem; reverse(num/10); } else return sum; return sum;}

To override a defined macro we can USE #ifdef and #undef preprocessors as follows:

• #ifdef A
• #undef A
• #endif
• #define A 10

If macro A is defined, it will be undefined USING undef and then defined again using define.

#include<stdio.h>STRUCT full_byte{char first : 4;char second : 4;};union A{char x;struct full_byte by;};MAIN(){char c = 100;union A a;a.x = c;PRINTF("the two nibbles are: %d and %d\n", a.by.first, a.by.second);}

Yes, we can COMPILE a program WITHOUT MAIN() function USING Macro.

E.g.

The FOLLOWING program will HELP you to remove duplicates from an ARRAY.