/**************************************************************************/
/*                                                                        */
/*  The Why platform for program certification                            */
/*                                                                        */
/*  Copyright (C) 2002-2014                                               */
/*                                                                        */
/*    Jean-Christophe FILLIATRE, CNRS & Univ. Paris-sud                   */
/*    Claude MARCHE, INRIA & Univ. Paris-sud                              */
/*    Yannick MOY, Univ. Paris-sud                                        */
/*    Romain BARDOU, Univ. Paris-sud                                      */
/*                                                                        */
/*  Secondary contributors:                                               */
/*                                                                        */
/*    Thierry HUBERT, Univ. Paris-sud  (former Caduceus front-end)        */
/*    Nicolas ROUSSET, Univ. Paris-sud (on Jessie & Krakatoa)             */
/*    Ali AYAD, CNRS & CEA Saclay      (floating-point support)           */
/*    Sylvie BOLDO, INRIA              (floating-point support)           */
/*    Jean-Francois COUCHOT, INRIA     (sort encodings, hyps pruning)     */
/*    Mehdi DOGGUY, Univ. Paris-sud    (Why GUI)                          */
/*                                                                        */
/*  This software is free software; you can redistribute it and/or        */
/*  modify it under the terms of the GNU Lesser General Public            */
/*  License version 2.1, with the special exception on linking            */
/*  described in file LICENSE.                                            */
/*                                                                        */
/*  This software is distributed in the hope that it will be useful,      */
/*  but WITHOUT ANY WARRANTY; without even the implied warranty of        */
/*  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.                  */
/*                                                                        */
/**************************************************************************/

typedef unsigned int uint;

#define MAXLEN 1000

typedef struct SparseArray {
  int val[MAXLEN];
  uint idx[MAXLEN], back[MAXLEN];
  uint n;
  uint sz;
} *sparse_array;

/*@ requires sz <= MAXLEN;
  @ ensures \fresh(\result,sizeof(struct SparseArray));
  @*/
sparse_array create(uint sz) {
  sparse_array a = (sparse_array)malloc(sizeof(struct SparseArray));
  a->n = 0;
  a->sz = sz;
  return a;
}

/*@ requires \valid(a);
  @*/
int get(sparse_array a, uint i) {
  if (a->idx[i] < a->n && a-> back[a->idx[i]] == i) return a->val[i];
  else return 0;
}

/*@ requires \valid(a);
  @*/
void set(sparse_array a, uint i, int v) {
  a->val[i] = v;
  if (!(a->idx[i] < a->n && a-> back[a->idx[i]] == i)) {
    //@ assert a->n < MAXLEN;
    a->idx[i] = a->n; a->back[a->n] = i; a->n++;
  }
}



int main() {
  sparse_array a = create(10), b = create(20);
  int x,y;
  x = get(a,5); y = get(b,7);
  //@ assert x == 0 && y == 0;
  set(a,5,1); set(b,7,2);
  x = get(a,5); y = get(b,7);
  //@ assert x == 1 && y == 2;
  x = get(a,0); y = get(b,0);
  //@ assert x == 0 && y == 0;
  return 0;
}





/*
Local Variables:
compile-command: "make sparse_array.why3ide"
End:
*/


