First N

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Problem statement

You are given a positive integer ‘N’. You have to find the sum of first ‘N’ natural numbers.

For Example:

If N = 3.
Sum of the first 3 natural numbers will be 1 + 2 + 3 = 6. Hence, the output will be 6.

Detailed explanation ( Input/output format, Notes, Images )

Input Format :

The first line of the input contains an integer, 'T’, denoting the number of test cases.

The first line of each test case contains a single positive integer ‘N’.

Output Format :

For each test case, print the sum of first ‘N’ natural numbers.

Print a separate line for each test case.

Note :

You do not need to print anything, it has already been taken care of. Just implement the given function.

Constraints :

1 <= T <= 10
1 <= N <= 10^6

Time limit: 1 sec

Sample Input 1 :

2
3
2

Sample output 1 :

6
3

Explanation For Sample Output 1 :

For the first test case,
N = 3.
Sum of the first 3 natural numbers will be 1 + 2 + 3 = 6. Hence, the output will be 6.

For the second test case,
N = 2.
Sum of the first 2 natural numbers will be 1 + 2 = 3. Hence, the output will be 3.

Sample Input 2 :

2
1
4

Sample output 2 :

1
10

Hint 1

Hint 2

Run a loop from 1 to ‘N’ and find the sum.

Approaches (2)

Approach 1

Approach 2

Brute Force

The idea of this approach is to go over each number from 1 to ‘N’ and add each number to the sum.

Here is the algorithm:

Declare a variable ‘sum’ and initialise it with 0.
Iterate from 1 to ‘N’(say iterator ‘i’)
- Update ‘sum’ as sum += i.
Return sum.

Time Complexity

O( N ), where ‘N’ is the given positive integer.

We go each number from 1 to ‘N’ exactly once.

Hence, the overall time complexity will be O(N).

Space Complexity

O( 1 )

We are not using any extra space.

Hence the overall space complexity will be O(1).

(100% EXP penalty)

First N

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