Siding window is a method for iterating over a linear collection by maintaining a window range indices (a group of consecutive elements) to satisfy the problem constraints

Sliding window is an improvement over brute force iteration to reduce the time complexity

Let's see a specific example

### Sliding window maximum problem

Given an array

`a`

and a number`k`

Write an algorithm to find the maximum sum of

`k`

consecutive elements in`a`

### Example

- Input [5, 7, 2, 9, 4] and 2, expected output 13

### Approach 1: Brute force

- Iterating over
`a`

one by one element to find max sum

```
```

- Output

```
13
```

Time complexity: O(n*k)

Space complexity: O(1)

### Approach 2: Sliding window

- Iterating over
`a`

window by window to find max sum

```
```

- Output

```
-9
```

Time complexity: O(n)

Space complexity: O(1)