Joel Antonio Delacruz Paredes - 3 months ago 5x

Python Question

`def singleNumber(nums):`

for num in set(nums):

return num if nums.count(num) != 2 #error occurs here

print(singleNumber([1,1,4,5,5]))

This follows the usual python condition expression format. I don't understand why it's giving me a syntax error here.

The purpose of this function is to find number that doesn't occur twice.

Answer

If you're going to execute a `return`

, you must return *something* no matter what.

Hence you could try:

```
return num if nums.count(num) != 2 else None
```

However, that's not going to work since it will return on the *first* check rather checking *all* the elements for what you want. In any case, I'm not *that* big a fan of post-conditions so I'd probably rewrite it as:

```
if nums.count(num) != 2: return num
```

This basically does what you need in that, if you *don't* explicitly return something (i.e., all of the numbers occur twice), the caller gets `None`

.

Source (Stackoverflow)

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