usaa20/cv6/a_station.c

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

struct station* create_station(){
   struct station* station = (struct station*)calloc(1,sizeof(struct station));
   station->tracks = (struct car**)calloc(STATION_SIZE, sizeof(struct car*));
   station->track_count = STATION_SIZE;
   return station;
}

void destroy_station(struct station* station){
    for(int i = 0; i < station->track_count; i++){
        //get one linked list from station
        struct car* this = station->tracks[i];
        while(this != NULL){
            struct car* delete = this;
            this = delete->next;
            free(delete);
        }
    }
    free(station->tracks);
    free(station);

}

int select_track(struct station* station, const char* target){
    unsigned int hash = 0;
    for(int i = 0; target[i] != '\0'; i++){
       //i used "lose lose" function, because it's simple and clear
       hash += target[i]; 
    }
    //change hash, so that it will be between 0 and station->track_count
    hash = hash % station->track_count;
    return hash;
}

void add_target_capacity(struct station* station,const char* target, int capacity){
    //find hash
    int track = select_track(station, target);

    //get right linked list(with help of hash)
    struct car* start = station->tracks[track];
    while(start != NULL){
        int x = strcmp(start->value, target);
        //if the "wagon" track and the target are the same, then increment capacity 
        if(x == 0){
            start->capacity = start->capacity + capacity;
            return;
        }
        start = start->next;
    }

    //if track is empty, create new "wagon"
    if(station->tracks[track] == NULL){
        struct car* new = calloc(1, sizeof(struct car));
        strcpy(new->value, target);
        new->capacity = capacity;
        new->next = start;
        station->tracks[track] = new;
    }
    return;   

}

int get_target_capacity(struct station* station,const char* target){
    //find hash
    int track = select_track(station, target);
    
    //get right linked list
    struct car* start = station->tracks[track];
    while(start != NULL){
        int x = strcmp(start->value, target);
        //if the "wagon" and the track are the same, than get the capacity 
        if(x == 0){
            return start->capacity;
        }
        start = start->next;
    }      
    return 0;
}

//count all tracks
int count_targets(struct station* station){
    int targets = 0;
    for(int i = 0; i < STATION_SIZE; i++){
        if(station->tracks[i] != NULL){
            targets++;
        }
    }
    return targets;
}
//count capacity in all tracks
int count_capacity(struct station* station){
    int capacity = 0;
    for(int i = 0; i < STATION_SIZE; i++){
        //get one linked list and count capacity there      
        struct car* this = station->tracks[i];
        if(this != NULL){
            capacity = capacity + this->capacity;
            this = this->next;
        }       
    }
    return capacity;
}