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  1. #include <stdlib.h>
  2. #include <stdio.h>
  3. #include <string.h>
  4. typedef struct node{
  5.     char course_name[50];
  6.     char course_number[50],next_course_number[50],prior_course_number[50];
  7.     struct node* next;
  8.     struct node* prior;
  9. }node;
  10. int main(){
  11.     int n;
  12.     if(scanf("%d",&n)!=1||n<=0)return 0;
  13.     node* course_list=(node*)malloc(sizeof(node)*n);
  14.     if(course_list==NULL)return 1;
  15.     for(int i=0;i<n;i++){
  16.         (course_list+i)->next=NULL;
  17.         (course_list+i)->prior=NULL;
  18.         if(scanf("%s %s %s %s",(course_list+i)->course_number,(course_list+i)->next_course_number,(course_list+i)->prior_course_number,(course_list+i)->course_name)!=4){
  19.             free(course_list);
  20.             return 1;
  21.         }
  22.     }
  23.     node* temp=NULL;
  24.     for(int i=0;i<n;i++){
  25.         if(strcmp((course_list+i)->prior_course_number,"0")==0){
  26.             temp=course_list+i;
  27.             break;
  28.         }
  29.     }
  30.     node* head=temp;
  31.     if(head==NULL){free(course_list);return 0;}
  32.     node* current_link=head;
  33.     current_link->prior=NULL;
  34.     for(int i=0;i<n;i++){
  35.         if(strcmp(current_link->next_course_number,"0")==0){
  36.             current_link->next=NULL;
  37.             break;
  38.         }
  39.         int found=0;
  40.         for(int k=0;k<n;k++){
  41.             if(strcmp((course_list+k)->course_number,current_link->next_course_number)==0){
  42.                 (course_list+k)->prior=current_link;
  43.                 current_link->next=(course_list+k);
  44.                 current_link=(course_list+k);
  45.                 found=1;
  46.                 break;
  47.             }
  48.         }
  49.         if(!found)break;
  50.     }
  51.     if(current_link!=NULL&&strcmp(current_link->next_course_number,"0")==0){
  52.         current_link->next=NULL;
  53.     }
  54.     char start_id[50],direction[5];
  55.     if(scanf("%s %s",start_id,direction)!=2){
  56.         free(course_list);
  57.         return 1;
  58.     }
  59.     node* current=head;
  60.     while(current!=NULL&&strcmp(current->course_number,start_id)!=0){
  61.         current=current->next;
  62.     }
  63.     if(current==NULL){
  64.         free(course_list);
  65.         return 0;
  66.     }else{
  67.         if(strcmp(direction,"next")==0){
  68.             while(current!=NULL){
  69.                 printf("%s\n",current->course_name);
  70.                 current=current->next;
  71.             }
  72.         }else if(strcmp(direction,"prior")==0){
  73.             while(current!=NULL){
  74.                 printf("%s\n",current->course_name);
  75.                 current=current->prior;
  76.             }
  77.         }
  78.     }
  79.     free(course_list);
  80.     return 0;
  81. }
Success #stdin #stdout 0.01s 5296KB
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203 204 202 History
202 203 201 Art
201 202 0 English
204 0 203 Biology
203 prior
stdout
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Standard output is empty
https://ideone.com/n026Ph
language:
C (gcc 8.3)
created:
3 hours ago
visibility:
public

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