Add new python 'unique elementes in list' answer

This commit is contained in:
surister 2019-11-28 11:01:35 +01:00
parent 31ae1ce379
commit 9ffbda01d2

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@ -2250,12 +2250,57 @@ def return_sum():
<details>
<summary>How do you swap values between two variables?</summary><br><b>
```
x, y = y, x
```
</b></details>
<details>
<summary>How to check if all the elements in a given lists are unique? so [1, 2, 3] is unique but [1, 1, 2, 3] is not unique but we 1 twice</summary><br><b>
</b></details>
<summary>How to check if all the elements in a given lists are unique? so [1, 2, 3] is unique but [1, 1, 2, 3] is not unique because 1 exists twice</summary><br><b>
</b>
There are many ways of solving this problem:
# Note: :list and -> bool are just python typings, they are not needed for the correct execution of the algorithm.
Taking advantage of sets and len:
```
def is_unique(l:list) -> bool:
return len(set(l)) == len(l)
```
This one is can be seen used in other programming languages.
```
def is_unique2(l:list) -> bool:
seen = []
for i in l:
if i in seen:
return False
seen.append(i)
return True
```
Here we just count and make sure every element is just repeated once.
```
def is_unique3(l:list) -> bool:
for i in l:
if l.count(i) > 1:
return False
return True
```
This one might look more convulated but hey, one liners.
```
def is_unique4(l:list) -> bool:
return all(map(lambda x: l.count(x) < 2, l))
```
</details>
<details>
<summary>What _ is used for in Python?</summary><br><b>
@ -2457,7 +2502,7 @@ will always return None regardless of the operations, therefore
```
def sum(a, b):
global C
global c
c = a + b
>>> None