Code for recursively reversing a linked list and recursively merging an ordered linked list

#include <stdio.h>struct node{    int val;    struct node *pNext;};struct node *gen(){    struct node *pHead = NULL;    for(int i = 10; i > 0; i--){        struct node * p = malloc(sizeof(struct node));        p -> val = i;        p -> pNext = pHead;        pHead = p;    }       return pHead;}void display(struct node *pHead) {    while( pHead != NULL)    {           printf("%d ", pHead->val);        pHead = pHead->pNext;    }       printf("\n");}struct node * reverse(struct node *pHead){    if (pHead == NULL || pHead -> pNext == NULL)    {           return pHead;    }       struct node *p = pHead -> pNext;    struct node *pNewHead =  reverse(p);    p -> pNext = pHead;    pHead ->pNext = NULL;    return pNewHead;}struct node * merge(struct node *pHeadA, struct node *pHeadB){    if(pHeadA == NULL )        return pHeadB;    if(pHeadB == NULL )        return pHeadA;    if(pHeadA -> val < pHeadB -> val)    {        pHeadA -> pNext = merge(pHeadA -> pNext, pHeadB);        return pHeadA;    }    else    {        pHeadB -> pNext = merge(pHeadA, pHeadB -> pNext);        return pHeadB;    }}int main(){    struct node *pHead = gen();    display(pHead);    struct node *pHeadB = gen();    pHead = merge(pHead, pHeadB),    display(pHead);    pHead = reverse(pHead);    display(pHead);}