# Sum of Integers

Easy
107
3
79.8% Acceptance

In this lab, you are tasked with implementing a method named `sumOfIntegers` in the `Main` class. This method should calculate the sum of all integers from 1 up to and including a given positive integer `n`.

## Requirements

• Create a method named `sumOfIntegers` in the `Main` class.
• The method should take one integer parameter `n`.
• It should return the sum of all integers from 1 to `n`.
• Consider edge cases, such as when `n` is 0.

## Edge Cases

1. When `n` is 0: The method should return 0, as there are no numbers to add.
2. Positive `n`: For any positive integer `n`, the method returns the sum of all integers from 1 to `n`.
3. Invalid `n`: Ensure your method handles unexpected inputs gracefully.

## Examples

1. sumOfIntegers(10): This should return `55`, as the sum of numbers from 1 to 10 is 55.
2. sumOfIntegers(7): For `n = 7`, the expected output is `28`, the sum of 1, 2, 3, 4, 5, 6, and 7.
3. sumOfIntegers(0): If `n` is 0, the method should return `0`, since there are no numbers to sum up.

Follow these guidelines to implement your method, and test it against the challenges provided to ensure it meets all the requirements.

## Challenges Information

### Challenge 1: Validate Method Name and Return Type

• Objective: Ensure the method `sumOfIntegers` is correctly defined in the `Main` class.
• Criteria:
• The method must be named `sumOfIntegers`.
• It should accept a single `int` parameter.
• The return type of the method should be `int`.

### Challenge 2: Correct Value for n = 10

• Objective: Test if the `sumOfIntegers` method returns the correct sum when `n` is 10.
• Criteria:
• Invoke `sumOfIntegers(10)`.
• The method should return `55`, the sum of integers from 1 to 10.

### Challenge 3: Correct Value for n = 0

• Objective: Ensure the `sumOfIntegers` method correctly handles the case where `n` is 0.
• Criteria:
• Invoke `sumOfIntegers(0)`.
• The expected return value should be `0`, as the sum from 1 to 0 is 0.

### Challenge 4: Correct Value for n = 7

• Objective: Check if the `sumOfIntegers` method returns the correct sum for `n` equal to 7.
• Criteria:
• Invoke `sumOfIntegers(7)`.
• The expected return value should be `28`, the sum of integers from 1 to 7.

### Challenge 5: Correct Value for n = 18

• Objective: Validate the correctness of the `sumOfIntegers` method for `n` equal to 18.
• Criteria:
• Invoke `sumOfIntegers(18)`.
• The expected return value should be `171`, the sum of all integers from 1 to 18.