usaa25/du5/a_station.c

#include "a_station.h"
#include <stdlib.h>
#include <string.h>
#include <stdio.h>

// funkcia pre vytvorenie stanice 
struct station* create_station(){
    // allokujeme dynamicke v pamati (na heape) pomocou calloc; vsetky byty su inticializovane na 0
    // tak tiez, allokujeme 1 krat
   struct station* station = (struct station*)calloc(1,sizeof(struct station));
   // double pointer: potrebujeme menit hodnotu; to je pointer na adresu ineho pointeru, a tot - na hodnotu.
   // Defaultne referencia je na prvy pointer pol'a. Allokacia 10 krat (makros)
   station->tracks = (struct car**)calloc(STATION_SIZE, sizeof(struct car*));
   station->track_count = STATION_SIZE;
   return station;
}
/// funkcia pre uvolnenie pamati
void destroy_station(struct station* station){
    /// prechadzanie a uvolnenie jednotlyvich linked listov a ich prvkov
    for(int i = 0; i<station->track_count; i++){
        struct car* tmp = station->tracks[i];
        while(tmp){
            struct car* toFree = tmp;
            tmp = tmp->next;
            free(toFree);


        }
    }
    // Mozeme uvolnit' array jednoducho, pretoze allokovali sme ho ako jeden 'kus'
    free(station->tracks);
    // uvolnenie stanice
    free(station);
}
// Heshovacia funckica
int select_track(struct station* station, const char* target){
    /// Pouzivame unsigned int pretoze cislo nesmie byt' zapornym
    unsigned int hash = 0;
    ///iteracia po prvkoch kluca
    for (int  i = 0; i < strlen(target); i++)
    /// Operator << je bitovy posun vl'avo. To iste ako vynasobit' nieco na 2^n.
    ///Napriklad <<6 je to iste ako * 2^6
    { hash += target[i] + (hash<<6) + (hash<<16) - hash;
        
    }
    /// Budeme mat' obrovske cislo na e vysledku, aj tak musime pouzit' mod velkos'ti pol'a.
    /// Index musi byt' v intervale od 0 do n-1.
    hash = hash %station->track_count;
    

    return hash;
}

// Funkica pre vytvorenie noveho nodu v poli alebo zvacsenie capacity
void add_target_capacity(struct station* station,const char* target, int capacity){
    // Dostaneme index
       int res = select_track(station, target);
       /// Pomocny pointer pre predchadzajucy
    struct car* previous = NULL;
    // adresa hlavy pre iteraciu. Prvok pod indexom. Vlasne, potrebuejeme vziat' adresu nodu, co robime.
    struct car** ptr = &station->tracks[res];
    //Berieme hodnotu - adresu pointeru pre iteraciu.
    struct car* head = *ptr;
/// Prechadzame po linked listu
   while(head){
    //Ak destinacia nodu a hl'adane su rovnake, tak zvacsime capacitu nodu a prerusime program.
    if(strcmp(head->value, target) == 0){
        head->capacity += capacity;
        return;
    }
    /// Prechadzame linked list
    previous = head;

    head = head->next;
    

   }
   // Ak sme vysli z cyklusu, to znamena ze polozka z prislusnym kl'ucom neexistuje a potrebuejeme vytvorit' nod.

   //Vytvorame nod a prerdaime hodnoty
   struct car* next = (struct car*)calloc(1, sizeof(struct car));
   strcpy(next->value, target);
   next->capacity = capacity;
   //Ak posledny nod nie je NULL, ho nasledujucy bude vytvoreny
   if(previous){
    previous->next = next;
   }
   //Inak, zoznam prazdny a pointer pojde na adresu v pamati vytvoreneho
   else{
    *ptr = next;
   }
}
   
/// Funkcia na dostanie capacity(hodnoty) kl'uca

int get_target_capacity(struct station* station,const char* target){
    /// Index res podl'a kl'uca 
    int res = select_track(station, target);
    /// Pointer na jednotlivy linked list 
    struct car** ptr = &station->tracks[res];
    /// Berieme prvy nod v nom pre prechadzanie, cize berieme hodnotu double pointeru;
    struct car* head = *ptr;
    /// pokial' nie jie NULL
    while (head)
    // Ak najdeme v linked liste s prislusnym indexom nod z kl'com hl'adanym, tak vratime hodnotu tho nodu (capacitu)
    {if(strcmp(head->value, target) == 0){
        return head->capacity;
    }
    /// prechadzanie
    head = head->next;
    }
   //Inak - nenajsli a vratime 0
    return 0;
}
// Funkcia pre pocet vsetkych destinacii
int count_targets(struct station* station){
    /// Ak je stanica NULL alebo pole NULL, vratime 0
    /// || - logicky operator OR v C
    if(station == NULL || station->tracks == NULL){
        return 0;
    }
     int total = 0;
     /// Iteracia po linked listoch pol'a
     for(int i = 0; i<station->track_count; i++){
        /// Pomocny pointer pre prechadzanie po jednotliyvych polozkach linked lista
        struct car* ptr = station->tracks[i];
        /// Incrementujeme pocet ak nie je to NULL, respektive je nejaka destinacia a prechadzame d'alej
        while(ptr){
            total++;
            ptr = ptr->next;
        }

    
}
/// Vratime pocet
return total;
}
/// Funkcia pre spocitanie vsetkych capacit (hodnot)
int count_capacity(struct station* station){
    // Ak stanica je NULL alebo pole je NULL - vratime 0
    if(station == NULL || station->tracks == NULL){
        return 0;
    }
    int total = 0;
    /// Iteracia po linked listoch v pole
    for(int i = 0; i<station->track_count; i++){
        /// Pomocny pointer pre prechadzanie
        struct car* ptr = station->tracks[i];
        while(ptr){
            /// Pripocitame capacitu nodu a pojdeme d'alej
            total += ptr->capacity;
            ptr = ptr->next;
        }

    }
    /// Vratime sucet
    return total;
}