C Program to Calculate Sum of Natural Numbers

 Here we will build a C program to calculate the sum of natural numbers using 4 different approaches i.e.

1. Using while loop
2. Using for loop
3. Using recursion
4. Using Functions

We will keep the same input in all the mentioned approaches and get an output accordingly.

Input: 

n = 10

Output: 

55 

Explanation: The sum of natural numbers up to a given number is 0+1+2+3+4+5+6+7+8+9+10=55

Approach 1: Using while loop 

The while loop executes the statements until the condition is false

Sum = 55

Time Complexity : O(n) as the loop runs for n iterations
Auxiliary Space : O(1) as only a fixed amount of memory is used.

Approach 2: Using for loop

For loop iterates up to n number of times.

Sum = 55

Time Complexity : O(n) as the loop runs for n+1 iterations.
Auxiliary Space : O(1) as only a fixed amount of memory is used.

Approach 3: Using recursion

Sum = 55

Time Complexity : O(n) as the function is called n+1 times.
Auxiliary Space : O(n) as each function call stores one value in the call stack, which consumes memory.

Approach 4: Using functions

Sum = 55

Time Complexity : O(n) as the loop runs for n+1 iterations.
Auxiliary Space : O(1) as only a fixed amount of memory is used.

Approach 5 : Using the formula sum of n natural numbers = n*(n+1)/2

Sum = 55

Time Complexity : O(1) as it performs a fixed number of operations regardless of the input size.
Auxiliary Space : O(1) as only a fixed amount of memory is used.