```# System Design question area
# long url
https://www.addgene.org/pooled-library/morris-lab-celltag/
# short url
https://www.addgene.org/ab1s3eef2
# base domain name that should stay consistent
https://www.addgene.org/
```
```java
// time O(N)
// sapce O(N)
list1 = [1,2,3]
list2 = [1,1,1]
public static List<Integer> getCommon(int[] list1, int[] list2) {
int n1 = list1.length;
int n2 = list2.length;
Set<Integer> set = new HashSet<>();
// O(N)
for (int i = 0; i < n1; i++) {
set.add(list1[i]);
}
Set<Integer> set2 = new HashSet<>();
// O(N)
for (int i = 0; i < n2; i++) {
// O(1)
if (set.contains(list2[i])) {
set2.add(list2[i]);
}
}
List<Integer> result = new ArrayList<>();
for (Integer element : set2) {
result.add(element);
}
return result;
}
```
``` Database Design Question
table name : Order
OrderID: String, Primary key
Name varchar(20)
Shipping_Street varchar(20)
Shipping_City varchar(20)
Shipping_state varchar(2) CA, MA, ME, ABC
Shipping_zip_code varchar(5) 04103
add
requirement : search the shipping address which is in Maine
select *
from XX table
where Shipping_state = "ME"
```