# Hash Function

## Problem

In data structure Hash, hash function is used to convert a string(or any other type) into an integer smaller than hash size and bigger or equal to zero. The objective of designing a hash function is to "hash" the key as unreasonable as possible. A good hash function can avoid collision as less as possible. A widely used hash function algorithm is using a magic number 33, consider any string as a 33 based big integer like follow:

hashcode("abcd")
= (ascii(a) * 33^3 + ascii(b) * 33^2 + ascii(c) *33 + ascii(d)) % HASH_SIZE
= (97* 33^3 + 98 * 33^2 + 99 * 33 +100) % HASH_SIZE
= 3595978 % HASH_SIZE

here HASH_SIZE is the capacity of the hash table (you can assume a hash table is like an array with index 0 ~ HASH_SIZE-1).

Given a string as a key and the size of hash table, return the hash value of this key.f

## Example

For key="abcd" and size=100, return 78

## Clarification

For this problem, you are not necessary to design your own hash algorithm or consider any collision issue, you just need to implement the algorithm as described.

## Code - Java

class Solution {
/**
* @param key: A String you should hash
* @param HASH_SIZE: An integer
* @return an integer
*/
public int hashCode(char[] key, int HASH_SIZE) {
long result = 0;
for (char c : key) {
result = (result * 33 + (int) c) % HASH_SIZE;
}
return (int) result;
}
};