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# 1390. Four Divisors

Given an integer array `nums`, return the sum of divisors of the integers in that array that have exactly four divisors.

If there is no such integer in the array, return `0`.

**Example 1:**

```
Input: nums = [21,4,7]
Output: 32
Explanation:
21 has 4 divisors: 1, 3, 7, 21
4 has 3 divisors: 1, 2, 4
7 has 2 divisors: 1, 7
The answer is the sum of divisors of 21 only.
```

**Constraints:**

* `1 <= nums.length <= 10^4`
* `1 <= nums[i] <= 10^5`

给定数组，返回有且只有四个除数的元素的除数之和。除数分布在square root两边，因此从平方根往下遍历到2，看是否只有一次能够整除。

```python
class Solution:
    def sumFourDivisors(self, nums: List[int]) -> int:
        res = 0
        for num in nums:
            if int(sqrt(num)) ** 2 == num:
                continue
            d = 0
            for i in range(2, int(sqrt(num)) + 1):
                if num % i == 0:
                    if d != 0:
                        d = 0
                        break
                    d = i
            if d != 0:
                res += sum([1, num, num // d, d])
        return res
                    
                
```