Sure, here is a step-by-step solution in Python:

1. First, we need to find the sum of the first n natural numbers. We can use the formula `n*(n+1)/2` to find this sum. Let's call this sum `expected_sum`.

```python
n = len(nums)
expected_sum = n*(n+1)//2
```

2. Next, we need to find the sum of the numbers in the given array. We can use the built-in `sum()` function in Python to find this sum. Let's call this sum `actual_sum`.

```python
actual_sum = sum(nums)
```

3. The missing number will be the difference between `expected_sum` and `actual_sum`.

```python
missing_number = expected_sum - actual_sum
```

4. Finally, we return the `missing_number`.

```python
return missing_number
```

So, the complete Python function to find the missing number is:

```python
def findMissingNumber(nums):
n = len(nums)
expected_sum = n*(n+1)//2
actual_sum = sum(nums)
missing_number = expected_sum - actual_sum
return missing_number
```

You can call this function with your array as the argument to find the missing number. For example:

```python
print(findMissingNumber([0, 1, 3]))
```

This will output `2`, which is the missing number in the array.

Question

Sure, here is a step-by-step solution in Python:

1. First, we need to find the sum of the first n natural numbers. We can use the formula `n*(n+1)/2` to find this sum. Let's call this sum `expected_sum`.

```python
n = len(nums)
expected_sum = n*(n+1)//2
```

2. Next, we need to find the sum of the numbers in the given array. We can use the built-in `sum()` function in Python to find this sum. Let's call this sum `actual_sum`.

```python
actual_sum = sum(nums)
```

3. The missing number will be the difference between `expected_sum` and `actual_sum`.

```python
missing_number = expected_sum - actual_sum
```

4. Finally, we return the `missing_number`.

```python
return missing_number
```

So, the complete Python function to find the missing number is:

```python
def findMissingNumber(nums):
    n = len(nums)
    expected_sum = n*(n+1)//2
    actual_sum = sum(nums)
    missing_number = expected_sum - actual_sum
    return missing_number
```

You can call this function with your array as the argument to find the missing number. For example:

```python
print(findMissingNumber([0, 1, 3]))
```

This will output `2`, which is the missing number in the array.

Knowee AI · Accepted Answer