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  1. #include<stdio.h>
  2. #include<stdlib.h>
  3. struct prefix {
  4.    unsigned int IP ;
  5.    unsigned char len ;
  6.   struct prefix *next ;
  7.  };
  8. typedef struct prefix Prefix ;
  9. int cal(int d){
  10.    int i , sum ;
  11.    sum = 2 ;
  12.    for( i = 0 ; i < d-1 ; i++)
  13.      sum = sum * 2 ;
  14.       return sum+1 ; }
  15.  
  16. Prefix *insert_a_node(Prefix *head,Prefix *node ){
  17.     Prefix *cur ;
  18.       cur = head ;
  19.     if(head == NULL)
  20.         return node ;
  21.     if( node == NULL )
  22.        return head ;
  23.     if( node->IP < head->IP)
  24.       { node->next = head ;
  25.           return node ;  }
  26.     while( cur->next != NULL && cur->next->IP <= node->IP)
  27.         cur = cur->next ;
  28.        node->next = cur->next ;
  29.        cur->next = node ;
  30.       return head ;
  31.                        }
  32.  
  33. void insert_prefix(Prefix *group_head,Prefix *node,int index){
  34.   int i = 0;
  35.   Prefix *t;
  36.  
  37.   if(node == NULL) return;
  38.   if(group_head->next == NULL)
  39.         {
  40.          group_head->next=node;
  41.          t = group_head;
  42.          return ;
  43.         }
  44.   if(node->IP <= group_head->next->IP)
  45.         {
  46.         node->next = group_head->next ;
  47.         group_head->next=node;
  48.         return ;
  49.         }
  50.   while(t->next!=NULL && t->next->IP < node->IP)
  51.         t=t->next;
  52.     node->next=t->next;
  53.     t->next=node;
  54.     return;
  55. }
  56. Prefix *build_list_no_order(Prefix *head,Prefix *node){
  57.  
  58.      if (head == NULL)
  59.          return node ;
  60.      if (node == NULL)
  61.         return head ;
  62.    Prefix *cur ;
  63.      cur = head ;
  64.    while ( cur->next != NULL)
  65.     cur = cur->next ;
  66.     cur->next = node ;
  67.   return head ;
  68.  
  69.  }
  70.  
  71. Prefix *build_routing_table(){
  72.     int a[5],i ;
  73.    int ip = 0 ;
  74.   Prefix *head ;
  75.       head =  NULL ;
  76.  FILE *ofp ;
  77.  ofp = fopen("routing_table","r") ;
  78.  while( fscanf(ofp,"%d.%d.%d.%d/%d",&a[0],&a[1],&a[2],&a[3],&a[4]) != EOF){
  79.        Prefix *node = (Prefix*)malloc(sizeof(Prefix)) ;
  80.    for ( i =0 ; i < 4 ; i++)
  81.    {  ip = ip + a[i] ;
  82.     if ( i != 3 )
  83.       ip = ip<<8 ;  }
  84.         node->IP = ip ;
  85.         ip = 0 ;
  86.         node->len=a[4];
  87.       head = build_list_no_order(head,node);  }
  88.     return head ;
  89.  
  90.     }
  91.  
  92. void segment(int d,Prefix *rout ,Prefix group[]){
  93.    int index=0,i;
  94.  
  95.    for(i=31 ; i>31-d ; i--){
  96.     if(rout->len<d)
  97.          index=cal(d)-1;
  98.     if( ( rout->IP & 1<<i ) && ( i!=32-d))
  99.         {index++;
  100.         index=index<<1;}
  101.     if( (rout->IP & 1<<i) && i==32-d)
  102.         index++;
  103.     if( !(rout->IP & 1<<i) && i!=32-d)
  104.         index=index<<1;
  105.       }
  106.    insert_prefix(&group[index],rout,index);
  107.  
  108.    }
  109. int main ( int argc , char *argv[]){
  110.   Prefix *head ;
  111.   Prefix *routing_head;
  112.   Prefix *trace_head;
  113.   Prefix *temp_rout ;
  114.   int d = 2 ; //need use argc finally
  115.   int group_num;
  116.   group_num = cal(d);
  117.   Prefix group[group_num] ;
  118.   trace_head = build_trace();
  119.   routing_head = build_routing_table();
  120.  
  121.  while(routing_head != NULL ){
  122.   segment(d,routing_head,group);
  123.   routing_head = routing_head->next;
  124.   }
  125.  
  126.      return 0 ;
  127. }
  128.  
Success #stdin #stdout 0s 4388KB
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stdout 
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https://ideone.com/CMiomt
language:
C (gcc 8.3)
created:
7 years ago
visibility:
secret

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