# C Exercises: Find the sum of specified series

## C Function : Exercise-5 with Solution

Write a program in C to find the sum of the series 1!/1+2!/2+3!/3+4!/4+5!/5 using the function.

**Pictorial Presentation:**

**Sample Solution:**

**C Code:**

```
#include <stdio.h>
int fact(int);
void main()
{
int sum;
sum=fact(1)/1+fact(2)/2+fact(3)/3+fact(4)/4+fact(5)/5;
printf("\n\n Function : find the sum of 1!/1+2!/2+3!/3+4!/4+5!/5 :\n");
printf("----------------------------------------------------------\n");
printf("The sum of the series is : %d\n\n",sum);
}
int fact(int n)
{
int num=0,f=1;
while(num<=n-1)
{
f =f+f*num;
num++;
}
return f;
}
```

Sample Output:

Function : find the sum of 1!/1+2!/2+3!/3+4!/4+5!/5 : ---------------------------------------------------------- The sum of the series is : 34

**Explanation:**

int fact(int n) { int num = 0, f = 1; while (num <= n - 1) { f = f + f * num; num++; } return f; }

In the above code the function 'fact' takes a single argument 'n' (type int). It computes the factorial of the input number 'n' using a while loop. The function initializes two local integer variables, 'num' and 'f', to 0 and 1 respectively. It then enters a loop that iterates n-1 times, incrementing num by 1 in each iteration. In each iteration of the loop, the value of f is updated by multiplying it with num incremented by 1. This computes the factorial of 'n' and returns the result.

**Time complexity and space complexity:**

The time complexity of the function 'fact' is O(n), where 'n' is the input number, as the loop in the function iterates n-1 times.

The space complexity of this function is O(1), as it only uses a fixed amount of memory to store the two integer variables 'num' and 'f'.

**Flowchart: **

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