Question

: (6 points) Typical hash function for a string key. Fill the missing line of code. Th hash function should compute a polynomial of the form: s[0] + s[1] * 37 + s[2] * 372 + s[3] * 373 + + s[n-l] * 37", where s[i] is the it character of string s, for i = 0, . . ., n-1. The length of string s is n. si size_t hash(const string &s) 1f const int n- s.length); for (int i = n-1; ǐ >= 0; --ǐ) { // Insert missing code below. hash value-... return hash value

Answer 1

The missing code:-

hash_value = hash_value + s[i] * pow(37, i);

The Complete hash function after adding missing line of code:-

#include <cmath>   // used for pow() function

size_t hash(const string &s) {

                size_t hash_value = 0;

                const int n = s.length();

                for(int i = n-1; i >= 0; --i) {

                                hash_value = hash_value + s[i] * pow(37,i);

                }

                return hash_value

}

Explaination of code:-

The above code will start with the value of i=n-1, so the polynomial will be computed as

s[n-1]*37^n-1 + s[n-2]*37^n-2 + ....................+ s[3]*37³ + s[2]*37² + s[1]*37 + s[0]