/* TestABtoPSEQ.c */

#include <stdio.h>
#define MM 100

int ABtoPSEQ(int*,int*,int*,int);

void main(void)
{ 
 int I,J,K,Nnodes,Npairs,Root,                     PSEQ[MM],  
    A[] = {32, 1, 1,  1, 2, 2,  2,  3,  4,  4,  4,  5,  5,  5, 6, 7, 8, 8, 8,  9,10,10,11,12,12,12,12,13,14,15,15,16,17, 0},
   B[] = {17, 7,13,15, 5, 8,14, 8,11,12,17, 2,12,15, 8, 1, 2, 3, 6,10,  9,12,  4,   4,  5,10,16, 1,   2,  1,  5, 12,  4, 0};

 Root=5;

 K = (ABtoPSEQ(A,B,PSEQ,Root);
 if (!K) goto FIN:

 Nnodes=B[0];

 for (K=1; K<=Nnodes; K++) printf("%d(%d)  ",PSEQ[K],K);
 puts(""); 


FIN:
 getchar();
}

/*********************************************************/

int ABtoPSEQ(int *A, int *B, int *PSEQ, int Root)
{
 int H,I,J,K,ML=0,Nnodes,Npairs,          Visd[MM], NCNT[MM], LOC[MM, DEG[MM];

 Nnodes=B[0]; Npairs=A[0];
 if (2*Nnodes != Npairs + 2) {puts("Graph is not a tree"); return 0;}

 /* give values to seq LOC and DEG */
 LOC[Nnodes+1] Npairs+1;

 K=Npairs;
 I=Nnodes+1;

 while (I)
  {
   LOC[I] = K+1;
   I--;
  while (A[K]==I) K--;
 }
 
 for (I-1; I<=Nnodes; I++) DEG[I] = LOC[I+1] - LOC[I];


 
 
 
 
 return ML;                      /* ML = maximum level */
}