95 lines
2.0 KiB
C
95 lines
2.0 KiB
C
#include <stdio.h>
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#include <stdlib.h>
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#include <string.h>
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#include "a_train.h"
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struct car *add_car(struct car *first, const char *target)
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{
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struct car *curr_car = (struct car*) calloc(1, sizeof(struct car));
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strcpy(curr_car -> value, target);
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curr_car -> next = NULL;
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if (first == NULL)
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{
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// create list if necessary
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return curr_car;
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}
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// add car to the end
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struct car *prev_car = first;
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while (prev_car -> next != NULL)
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{
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prev_car = prev_car -> next;
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}
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prev_car -> next = curr_car;
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return first;
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}
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void print_train(struct car *first)
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{
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struct car *curr_car = first;
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while (curr_car != NULL)
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{
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printf("%s\n", curr_car -> value);
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curr_car = curr_car -> next;
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}
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}
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void cancel_train(struct car *first)
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{
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if (first == NULL)
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{
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return;
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}
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cancel_train(first->next);
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free(first);
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}
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struct car *clear_train(struct car *first, const char *target)
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{
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if (first == NULL)
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{
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return NULL;
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}
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if (strcmp(first -> value, target) == 0)
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{
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struct car *answer = first -> next;
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free(first);
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return answer;
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}
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struct car *prev_car = first;
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struct car *curr_car = first -> next;
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if (prev_car == NULL)
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{
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return first;
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}
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while ((prev_car -> next) != NULL) {
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curr_car = prev_car -> next;
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if(curr_car == NULL)
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{
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break;
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}
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// if found target
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if (strcmp(curr_car -> value, target) == 0)
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{
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// remove it and continue
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struct car *next_car = curr_car -> next;
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free(curr_car);
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prev_car -> next = next_car;
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prev_car = next_car;
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}
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else
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{
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prev_car = curr_car;
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}
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if (prev_car == NULL)
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{
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break;
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}
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}
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return first;
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}
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