BUPT-homework/semester3/exercises/3-Lists-Stacks-and-Queues/exercise3.6.c

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

typedef struct ListNode {
  int val;
  struct ListNode *next;
} ListNode;

ListNode *appendNode(ListNode *node, int val) {
  ListNode *new = malloc(sizeof(ListNode));
  node->next = new;

  new->next = NULL;
  new->val = val;

  return new;
}

void freeNode(ListNode *head) {
  ListNode *ptr = head;
  do {
    head = ptr;
    ptr = ptr->next;
    free(head);
  } while (ptr != NULL);
}

void printNode(ListNode *head) {
  ListNode *ptr = head;

  while (ptr != NULL) {
    printf("%d->", ptr->val);
    ptr = ptr->next;
  }

  printf("NULL\n");
}

ListNode *addList(ListNode *l, ListNode *r) {
  ListNode *head = malloc(sizeof(ListNode));
  head->val = l->val + r->val;

  ListNode *ptr = head;
  ListNode *ptrL = l->next;
  ListNode *ptrR = r->next;
  while (ptrL && ptrR) {
    ptr = appendNode(ptr, ptrL->val + ptrR->val);
    ptrL = ptrL->next;
    ptrR = ptrR->next;
  }

  while (ptrL) {
    ptr = appendNode(ptr, ptrL->val);
    ptrL = ptrL->next;
  }

  while (ptrR) {
    ptr = appendNode(ptr, ptrR->val);
    ptrR = ptrR->next;
  }

  return head;
}

int main(void) {
  ListNode *l = malloc(sizeof(ListNode));
  ListNode *r = malloc(sizeof(ListNode));

  ListNode *ptrL = l;
  ListNode *ptrR = r;

  // input
  int lLen, rLen;
  scanf("%d", &lLen);
  scanf("%d", &rLen);
  int temp;

  for (int i = 0; i < lLen; i++) {
    scanf("%d", &temp);
    ptrL = appendNode(ptrL, temp);
  }
  printNode(l->next);

  for (int i = 0; i < rLen; i++) {
    scanf("%d", &temp);
    ptrR = appendNode(ptrR, temp);
  }
  printNode(r->next);

  // add
  ListNode *ans = addList(l->next, r->next);
  printNode(ans);

  freeNode(l);
  freeNode(r);
  freeNode(ans);

  return 0;
}