Create a function str_hash that takes a string str as an input parameter and returns its hash value. The hash value for this problem is defined by the following formula n 1 i = 0 s t r [ i ] 31 i , where str[i] corresponds to the ascii value of the character at index i. The following condition has to hold: if two strings are equal, then also their hashes have to be equal. Notice, the contrary doesnt have to hold, that is, if the hashes are equal then the strings do not necessarily have to be equal.

The function name and parameters are as following:

unsigned long long str_hash(const char *str);

must be typed in C++ and can only use #include and or