// my solution has got a time limit

below is my code
// -------------------
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#define maxn 7503
typedef struct ttnode *tnode;
struct ttnode { long w; tnode next; };
tnode list[maxn],first[maxn];
long w,n,min,m,l=0,l2,deg[maxn],dat[maxn],used
[maxn],top,ptemp,ntemp;
long index_prev[maxn],index_next[maxn];
int add(int w1,int w2)
{
    tnode now=(tnode)malloc(sizeof(struct ttnode));
    long  temp;
    now->w=w2; now->next=first[w1];
    first[w1]=now;

    while (now->next !=NULL && (now->next)->w < (now->w) )
    {
        temp=now->w;
        now->w=(now->next)->w;
        (now->next)->w=temp;
        now=now->next;
    }

    return 0;
}

int main()
{
    tnode now;

    index_next[0]=1;
    for (l=0; l<maxn; l++)
    {
       deg[l]=0; used[l]=0;
    }
    l=0;


    while ( scanf("%ld",&w) != EOF )
    {
        l++; dat[l]=w;
        deg[w]++;
    }

    n=l+1;
    for (l=1; l<=n; l++)
    { index_prev[l]=l-1; index_next[l]=l+1; }
    for (l=1; l<=n; l++) list[l]=NULL;
    for (l=1; l<=n; l++) deg[l]++;
    for (l=1; l<=n-1; l++)
       {
          l2=index_next[0];
          while (l2<n+1)
          {
         if (deg[l2]==1)
         { m=l2; break; }
         l2=index_next[l2];
          }
          ntemp=index_next[m]; ptemp=index_prev[m];
          index_prev[ ntemp ]=ptemp;
          index_next[ ptemp ]=ntemp;
          deg[m]--; deg[ dat[l] ]--;
          add(m,dat[l]);
          add(dat[l],m);
       }
    for (l=1; l<=n; l++)
    {
       printf("%ld: ",l);
       now=first[l];
       while (now!=NULL) { printf("%ld ",now->w); now=now-
>next; }
       printf("\n");
    }
    return 0;
}