---
id: 69bc6cb30c1d112a2e110a09
title: "Challenge 252: Unique Stair Climber"
challengeType: 29
dashedName: challenge-252
---

# --description--

Given a number of stairs, return how many distinct ways someone can climb them taking either 1 or 2 steps at a time.

# --hints--

`get_unique_climbs(4)` should return `5`.

```js
({test: () => { runPython(`
from unittest import TestCase
TestCase().assertEqual(get_unique_climbs(4), 5)`)
}})
```

`get_unique_climbs(5)` should return `8`.

```js
({test: () => { runPython(`
from unittest import TestCase
TestCase().assertEqual(get_unique_climbs(5), 8)`)
}})
```

`get_unique_climbs(10)` should return `89`.

```js
({test: () => { runPython(`
from unittest import TestCase
TestCase().assertEqual(get_unique_climbs(10), 89)`)
}})
```

`get_unique_climbs(18)` should return `4181`.

```js
({test: () => { runPython(`
from unittest import TestCase
TestCase().assertEqual(get_unique_climbs(18), 4181)`)
}})
```

`get_unique_climbs(29)` should return `832040`.

```js
({test: () => { runPython(`
from unittest import TestCase
TestCase().assertEqual(get_unique_climbs(29), 832040)`)
}})
```

`get_unique_climbs(50)` should return `20365011074`.

```js
({test: () => { runPython(`
from unittest import TestCase
TestCase().assertEqual(get_unique_climbs(50), 20365011074)`)
}})
```

# --seed--

## --seed-contents--

```py
def get_unique_climbs(steps):

    return steps
```

# --solutions--

```py
def get_unique_climbs(steps):
    if steps <= 0:
        return 0
    if steps == 1:
        return 1
    if steps == 2:
        return 2
    prev2, prev1 = 1, 2
    for _ in range(3, steps + 1):
        prev2, prev1 = prev1, prev2 + prev1
    return prev1
```