1  /* A Fibonacci heap datatype.
       2     Copyright (C) 1998-2023 Free Software Foundation, Inc.
       3     Contributed by Daniel Berlin (dan@cgsoftware.com).
       4  
       5  This file is part of GCC.
       6     
       7  GCC is free software; you can redistribute it and/or modify it
       8  under the terms of the GNU General Public License as published by
       9  the Free Software Foundation; either version 2, or (at your option)
      10  any later version.
      11  
      12  GCC is distributed in the hope that it will be useful, but
      13  WITHOUT ANY WARRANTY; without even the implied warranty of
      14  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
      15  General Public License for more details.
      16  
      17  You should have received a copy of the GNU General Public License
      18  along with GCC; see the file COPYING.  If not, write to
      19  the Free Software Foundation, 51 Franklin Street - Fifth Floor,
      20  Boston, MA 02110-1301, USA.  */
      21  
      22  /* Fibonacci heaps are somewhat complex, but, there's an article in
      23     DDJ that explains them pretty well:
      24  
      25     http://www.ddj.com/articles/1997/9701/9701o/9701o.htm?topic=algoritms
      26  
      27     Introduction to algorithms by Corman and Rivest also goes over them.
      28  
      29     The original paper that introduced them is "Fibonacci heaps and their
      30     uses in improved network optimization algorithms" by Tarjan and
      31     Fredman (JACM 34(3), July 1987).
      32  
      33     Amortized and real worst case time for operations:
      34  
      35     ExtractMin: O(lg n) amortized. O(n) worst case.
      36     DecreaseKey: O(1) amortized.  O(lg n) worst case. 
      37     Insert: O(2) amortized. O(1) actual.  
      38     Union: O(1) amortized. O(1) actual.  */
      39  
      40  #ifndef _FIBHEAP_H_
      41  #define _FIBHEAP_H_
      42  
      43  #include "ansidecl.h"
      44  
      45  #ifdef __cplusplus
      46  extern "C" {
      47  #endif
      48  
      49  typedef long fibheapkey_t;
      50  
      51  typedef struct fibheap
      52  {
      53    size_t nodes;
      54    struct fibnode *min;
      55    struct fibnode *root;
      56  } *fibheap_t;
      57  
      58  typedef struct fibnode
      59  {
      60    struct fibnode *parent;
      61    struct fibnode *child;
      62    struct fibnode *left;
      63    struct fibnode *right;
      64    fibheapkey_t key;
      65    void *data;
      66  #if defined (__GNUC__) && (!defined (SIZEOF_INT) || SIZEOF_INT < 4)
      67    __extension__ unsigned long int degree : 31;
      68    __extension__ unsigned long int mark : 1;
      69  #else
      70    unsigned int degree : 31;
      71    unsigned int mark : 1;
      72  #endif
      73  } *fibnode_t;
      74  
      75  extern fibheap_t fibheap_new (void);
      76  extern fibnode_t fibheap_insert (fibheap_t, fibheapkey_t, void *);
      77  extern int fibheap_empty (fibheap_t);
      78  extern fibheapkey_t fibheap_min_key (fibheap_t);
      79  extern fibheapkey_t fibheap_replace_key (fibheap_t, fibnode_t,
      80                                           fibheapkey_t);
      81  extern void *fibheap_replace_key_data (fibheap_t, fibnode_t,
      82                                         fibheapkey_t, void *);
      83  extern void *fibheap_extract_min (fibheap_t);
      84  extern void *fibheap_min (fibheap_t);
      85  extern void *fibheap_replace_data (fibheap_t, fibnode_t, void *);
      86  extern void *fibheap_delete_node (fibheap_t, fibnode_t);
      87  extern void fibheap_delete (fibheap_t);
      88  extern fibheap_t fibheap_union (fibheap_t, fibheap_t);
      89  
      90  #ifdef __cplusplus
      91  }
      92  #endif
      93  
      94  #endif /* _FIBHEAP_H_ */