SLL

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

#define TYPE int

typedef struct Node{
    TYPE data;
    struct Node *next;
}Node;

void reset(Node **lsHead);
int isEmpty(Node **lsHead);
void addToStart(Node **lsHead,TYPE val);
void addToEnd(Node **lsHead,TYPE val);
TYPE popStart(Node **lsHead);
TYPE popEnd(Node **lsHead);

int main(){
    system("clear");
    Node *ls = NULL; reset(&ls);
    addToStart(&ls,5);
    addToStart(&ls,4);
    addToEnd(&ls,6);
    printf("pop end: %d\n", popEnd(&ls));
    printf("pop start: %d\n", popStart(&ls));
    printf("pop end: %d\n", popEnd(&ls));
    return 0;
}

void reset(Node **lsHead){ *lsHead = NULL; }
int isEmpty(Node **lsHead){ return !*lsHead; }
void addToStart(Node **lsHead,TYPE val){
    Node *node = (Node*) malloc(sizeof(Node));
    node->data = val;
    node->next = *lsHead;
    *lsHead = node;
}
void addToEnd(Node **lsHead,TYPE val){
    Node *node = (Node*) malloc(sizeof(Node));
    node->data = val; node->next = NULL;
    if(isEmpty(lsHead))
        *lsHead = node;
    else{
        Node *last = *lsHead;
        while(last->next) last = last->next; // getting the latest node
        last->next = node;
    }
}
TYPE popStart(Node **lsHead){
    if(!isEmpty(lsHead)){
        TYPE val = (*lsHead)->data;
        Node *start = *lsHead;
        free(start);
        *lsHead = (*lsHead)->next;
        return val;
    }
    return 1<<31;
}
TYPE popEnd(Node **lsHead){
    if(!isEmpty(lsHead)){
        Node *preLast = *lsHead;
        if(preLast->next && preLast->next->next)
            while((preLast->next)->next)
                preLast = preLast->next;
        Node * last = preLast->next;
        if(!last){
            // last node in list
            TYPE val = preLast->data;
            free(preLast);
            reset(lsHead);
            return val;
        }else{
            // not last node
            TYPE val = last->data;
            preLast->next = NULL;
            free(last);
            return val;
        }

    }
    return 1<<31;
}