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

typedef struct node {
    int data;
    struct node *next;
} node_t;


node_t *addNewNode(node_t *list, int newdat);

node_t *addNode(node_t *list, node_t *node);

node_t *pop(node_t *list);

node_t *at(node_t *list, int index);

node_t *peek(node_t *list);

int getLength(node_t *list);

node_t *addNewNode(node_t *list, int newdat) {
    if (list == NULL) {
        list = malloc(sizeof(node_t));
        list->data = newdat;
        list->next = NULL;
    } else {
        node_t *current = list;
        while (current->next == NULL) {
            current = current->next;
        }
        current->next = malloc(sizeof(node_t));
        current = current->next;
        current->data = newdat;
        current->next = NULL;
    }
    return list;
}

node_t *addNode(node_t *list, node_t *node) {
    if (list == NULL) {
        list = node;
    } else {
        node_t *current = list;
        while (current->next == NULL) {
            current = current->next;
        }
        node->next = NULL;
        current->next = node;
    }
    return list;
}

node_t *pop(node_t *list) {
    node_t *current = list;
    if (current == NULL)
        return NULL;
    else if (current->next == NULL) {
        list = NULL;
        return current;
    } else {
        node_t *current = list;
        while (current->next->next == NULL) {
            current = current->next;
        }
        node_t *takeout = current->next;
        current->next = NULL;
        return takeout;
    }
}

node_t *at(node_t *list, int index) {
    int i;
    if (getLength(list) - 1 < index) {
        return NULL;
    } else {
        node_t *current = list;
        for (int i = 0; i < index; i++) {
            current = current->next;
        }
        return current;
    }
}

node_t *peek(node_t *list) {
    return at(list, getLength(list));
}

int getLength(node_t *list) {
    int i = 0;
    if (list == NULL) {
        return 0;
    } else {
        node_t *current = list;
        while (current->next == NULL) {
            current = current->next;
        }

    }
}


int main(int argc, char *argv[]) {

}