c - Linking and assigning struct elements to random nodes -

this problem:

basically, given large file (think 20000+ lines of text) contains following: line 1: <number_of_nodes> <number of edges>
rest: <source> <destination> <cost>
goal figure out memory efficient way create structure(s) allow associate nodes connected nodes. these connections bidirectional.

the user should allowed input location/node , program must output neighbors of node , corresponding cost input node each of neighbors.

*note: |large files| contain 25000 lines of text in format

integer integer integer 

here's supposed output:

number of nodes 25000  enter node examine: 0 neighbors of node 0 are: node 1 cost 450 node 100 cost 1130  enter node examine:0 neighbors of node 0 are: node 4 cost 850 node 91 cost 304   enter node examine: 0 neighbors of node 0 are: node 3 cost 230 node 11 cost 330  enter node examine: exit 

and here's i've tried:

#include <stdio.h> #include <stdlib.h>  struct graph {     int src;     int dest;     int cost; }pathedge;  int main() {     int nlines, i,v;     char r;     int ecost,ebegin, eend;      scanf(“%s”,&nlines);      pathedge[nlines + 1];      for(i = 0; < nlines; i++) {         scanf("%d, %d, %d\n", &ebegin, &eend, &ecost);         edges[i].begin = ebegin;         edges[i].end = eend;         edges[i].cost = ecost;         struct town         {             struct town *north;             int name[25000];         };         struct town *root, *current;         root = (struct town *) malloc (sizeof (struct town));         root->north = null;         strcpy (root->name,ecost);         current = (struct town *) malloc (sizeof (struct town));         current->north = root;         strcpy (current->name, ecost);         strcpy(ecost,”node %d”,i);     }      printf(“%d”,sizeof(int name));     printf(“please enter node want examine. if want exit, please press ‘x’.\n”);     scanf(“%c”,&r);      switch(r)     {     case ‘x’:     case ‘x’:         printf(“you entered wrong value. gomen. try again.\n”);         break;     default:         if(0<r<25000)         {             printf(“you have accessed node %d\n”,r);             printf(“its neighboring nodes %d\n %d\n”,ecost[nlines+1],ecost[nlines+2]);         }         else         {             printf(“invalid input again. please try again. thanks\n”);         }         break;     }     return 0; }