BUPT-homework/semester3/pset1/7-3-central-list.c

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

typedef struct listNode {
  int id;
  struct listNode *next;
} listNode;

listNode *appendNode(int id, listNode *head) {
  listNode *new = malloc(sizeof(listNode));
  new->id = id;
  new->next = NULL;

  head->next = new;
  return new;
}

int main(void) {
  listNode* head = malloc(sizeof(listNode));
  listNode* ptr = head;

  int size = 0;
  int buf;
  while ((scanf("%d,", & buf) != EOF)) {
    ptr = appendNode(buf, ptr);
    size++;
  }

  if (size <= 1) {
    printf("Yes");
    return 0;
  }

  int ans[size];

  head = head->next;
  for (int i = 0; i < size; i ++) {
    ans[i] = head->id;
    head = head->next;
  }

  int isCentral = 1;
  for (int i = 0, end = size / 2; i < end; i++) {
    if (ans[i] != ans[size - i - 1]) {
      isCentral = 0;
    }
  }

  if (isCentral == 1) {
    printf("Yes");
  } else {
    printf("No");
  }

  return 0;
}