# Rehashing

The size of the hash table is not determinate at the very beginning. If the total size of keys is too large (e.g. size >= capacity / 10), we should double the size of the hash table and rehash every keys. Say you have a hash table looks like below:

```
size=3, capacity=4
[null, 21, 14, null]
↓ ↓
9 null
↓
null
```

The hash function is:

```
int hashcode(int key, int capacity) {
return key % capacity;
}
```

Here we have three numbers, `9`

, `14`

and `21`

, where `21`

and `9`

share the same position as they all have the same hashcode `1`

(21 % 4 = 9 % 4 = 1). We store them in the hash table by linked list.

Rehashing this hash table, double the capacity, you will get:

```
size=3, capacity=8
index: 0 1 2 3 4 5 6 7
hash : [null, 9, null, null, null, 21, 14, null]
```

For this problem, given the original hash table, return the new hash table after rehashing.

Notice

For negative integer in hash table, the position can be calculated as follow:

C++/Java: if you directly calculate `-4 % 3`

you will get `-1`

. You can use function: `a % b = (a % b + b) % b`

to make it is a non negative integer.
Python: you can directly use `-1 % 3`

, you will get `2`

automatically.

Example

```
Original Table:
[null, 21, 14, null]
↓ ↓
9 null
↓
null
Rehashed Table:
[null, 9, null, null, null, 21, 14, null]
↓ ↓ ↓
null null null
```