cs240.c

#define MINERAL_LEN (50)

#include <assert.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>

typedef struct rock {
    char mineral[MINERAL_LEN];
    float mass;
    struct rock* prev_node;
    struct rock* next_node;
} rock_t;

rock_t* create(char* mineral, float mass) {
    assert(mineral != NULL);

    rock_t* created = malloc(sizeof(rock_t));
    assert(created != NULL);

    strncpy(created->mineral, mineral, MINERAL_LEN);
    created->mineral[MINERAL_LEN] = '\0';

    created->mass = mass;
    created->next_node = NULL;
    created->prev_node = NULL;

    return created;
}

rock_t* swap_rocks(rock_t* fst_node, rock_t* snd_node) {
    assert(fst_node);
    assert(snd_node);

    rock_t* head = fst_node;
    while (head->prev_node)
        head = head->prev_node;

    char mineral_swap[MINERAL_LEN] = "";
    strcpy(mineral_swap, fst_node->mineral);
    strcpy(fst_node->mineral, snd_node->mineral);
    strcpy(snd_node->mineral, mineral_swap);

    float mass_swap = fst_node->mass;
    fst_node->mass = snd_node->mass;
    snd_node->mass = mass_swap;

    return head;
}

rock_t* find_head(rock_t* node) {
    while (node->prev_node)
        node = node->prev_node;

    return node;
}

void print_list(rock_t* head) {
    if (head) {
        printf("Mineral: %s, Mass: %f\n", head->mineral, head->mass);
        print_list(head->next_node);
    }
}

rock_t* append(rock_t* head, char* mineral, float mass) {
    rock_t* node = create(mineral, mass);
    head->next_node = node;
    node->prev_node = head;
    return node;
}

int main() {
    rock_t* node_1 = create("Min 1", 1.0);
    rock_t* node_2 = append(node_1, "Min 2", 2.0);                              
    rock_t* node_3 = append(node_2, "Min 3", 3.0);
    rock_t* node_4 = append(node_3, "Min 4", 4.0);
    rock_t* node_5 = append(node_4, "Min 5", 5.0);

    printf("-----------\n");
    print_list(node_1);
    printf("-----------\n");

    rock_t* head = swap_rocks(node_2, node_4);
    printf("-----------\n");
    print_list(head);
    printf("-----------\n");

    head = swap_rocks(node_3, node_5);
    printf("-----------\n");
    print_list(head);
    printf("-----------\n");

    head = swap_rocks(node_1, node_5);
    printf("-----------\n");
    print_list(head);
    printf("-----------\n");
}

out.txt

-----------
Mineral: Min 1, Mass: 1.000000
Mineral: Min 2, Mass: 2.000000
Mineral: Min 3, Mass: 3.000000
Mineral: Min 4, Mass: 4.000000
Mineral: Min 5, Mass: 5.000000
-----------
-----------
Mineral: Min 1, Mass: 1.000000
Mineral: Min 4, Mass: 4.000000
Mineral: Min 3, Mass: 3.000000
Mineral: Min 2, Mass: 2.000000
Mineral: Min 5, Mass: 5.000000
-----------
-----------
Mineral: Min 1, Mass: 1.000000
Mineral: Min 4, Mass: 4.000000
Mineral: Min 5, Mass: 5.000000
Mineral: Min 2, Mass: 2.000000
Mineral: Min 3, Mass: 3.000000
-----------
-----------
Mineral: Min 3, Mass: 3.000000
Mineral: Min 4, Mass: 4.000000
Mineral: Min 5, Mass: 5.000000
Mineral: Min 2, Mass: 2.000000
Mineral: Min 1, Mass: 1.000000
-----------