Question

/*

Write a function that looks for a particular person in their respective linked list

The only place you need to write code is the "find" method in the linked list class

*/

#include <bits/stdc++.h>

using namespace std;

string ltrim(const string &);
string rtrim(const string &);

#define BUFFLEN 10
/*
Each "person" is defined by their name, zipcode, and their pet's name.
Persons are hashed by their zipcode.
*/

//----------------------------------------------------------------------------
/* function declarations
------------------------*/
int computeKey(int);
void add_to_buffer(string,int,string);
void find_in_buffer(int);

//----------------------------------------------------------------------------
/* define a "person"
--------------------*/
class person{
public:

// variables that define a person
string name;
int zipcode;
string petsname;
person *next;

// constructor
person(string nm, int zc, string pn, person *n=NULL){
name = nm;
zipcode = zc;
petsname = pn;
next = n;
}

// print a person
void print(){
cout << name << " lives in " << zipcode << " with pet " << petsname << endl;
}w
};

//----------------------------------------------------------------------------
/* define a Linked List
-------------------------*/
class LL{
public:

// just the one variable
person *head;

// constructor
LL(){head=NULL;}
  
// create a new person and push them onto the List
void push(string nm, int zc, string pn){
person *p = new person(nm,zc,pn,head);
head = p;
}

// find a person in the list
// inputs provided: the person's zipcode
// return: a pointer to either the person or to NULL (if the person isn't found)
person *find(int zc){
// --------------------
// YOUR CODE GOES HERE
// --------------------
}
};

//--t--------------------------------------------------------------------------
/* Define the buffer, which is an array of Linked Lists
-------------------------------------------------------*/
LL buffer[BUFFLEN];

//----------------------------------------------------------------------------
/* Function definitions
-------------------------------------------------------*/

void add_to_buffer(string nm, int zc, string pn){
int key = computeKey(zc);
buffer[key].push(nm,zc,pn);
}

int computeKey(int val){
return val%BUFFLEN;
}

void find_in_buffer(int zc){
int key = computeKey(zc);
person *p = buffer[key].find(zc);
if (p!=NULL)
p->print();
else
cout << zc << " not found" << endl;
}

void test_buffer(int zip) {
add_to_buffer("alice",19122,"hoot");
add_to_buffer("bob",12193,"rover");
add_to_buffer("charlie",27707,"lady");
add_to_buffer("dan",90210,"bubbles");
add_to_buffer("elise",20904,"marbles");
add_to_buffer("fran",86753,"moose");
  
find_in_buffer(zip);
}

int main()
{
string zip_temp;
getline(cin, zip_temp);

int zip = stoi(ltrim(rtrim(zip_temp)));

test_buffer(zip);

return 0;
}

string ltrim(const string &str) {
string s(str);

s.erase(
s.begin(),
find_if(s.begin(), s.end(), not1(ptr_fun<int, int>(isspace)))
);

return s;
}

string rtrim(const string &str) {
string s(str);

s.erase(
find_if(s.rbegin(), s.rend(), not1(ptr_fun<int, int>(isspace))).base(),
s.end()
);

return s;
}

Answer 1

////////////////// find method //////////////////

person *find(int zc){
    /*
    *  the process goes as follow
    *  initially the head is pointed to first node of that index
    *  now we are creating a temp pointer and pointing to head node i.e. first node
    *  then we traverse through all nodes by setting temp node to be its next node until the temp node becomes null
    *  at any iteration if temp node's zipcode equals the given zc then it returns that pointer 
    *  if no node is found with the required zc then it exists while loop and returns null
    *  */
    person *temp =head;   // create a temp pointer that points to head node 
    
    while(temp!=NULL){       
        if(temp->zipcode==zc){
            return temp;
        }
        temp=temp->next;
    }
    return NULL;
}
};