Solving algorithms tasks.

Time: 31 ms,

Faster than 2.57% of Java online submissions.

We use split string S and J into arrays. After we create a hashmap of S, where a key is a letter and value number of this letters in S. The last step is to find what letters from J exist in this hashmap and sum values.

Time: 72 ms,

Faster than 22.96% of Java online submissions.

Firstly we check that emails are correct (1 <= emails.length() <= 100; 1 <= emails[i] <= 100; every email contains only 1 @ symbol. Secondly, we split email by "@", and remove all after "+". After we remove dots.

Create a new set, save emails and get size of this set.

Time: 400 ms,

Faster than 42.19% of C# online submissions for Two Sum.

Memory Usage: 30.5 MB, less than 92.69% of C# online submissions for Two Sum.

There is an input array and an input target int values. Program should find 2 indices for which values sum is equal to target.

Starts from the first number, check if it sum with next value is equal to target; when array ends, start comparing for second number; and do it until there is end of the array.