One of the major differences between combinatorial computing and other areas of computing such as statistics, numerical analysis and linear programming is the use of complex data types. Whilst the built-in types, such as integers, reals, vectors, and matrices, usually suffice in the other areas, combinatorial computing relies heavily on types like stacks, queues, dictionaries, sequences, sorted sequences, priority queues, graphs, points, segments, … In the fall of 1988, we started a project (called LEDA for Library of Efficient Data types and Algorithms) to build a small, but growing library of data types and algorithms in a form which allows them to be used by non-experts. We hope that the system will narrow the gap between algorithms research, teaching, and implementation. The main features of LEDA are:
1. LEDA provides a sizable collection of data types and algorithms in a form which allows them to be used by non-experts. In the current version, this collection includes most of the data types and algorithms described in the text books of the area.
2. LEDA gives a precise and readable specification for each of the data types and algorithms mentioned above. The specifications are short (typically, not more than a page), general (so as to allow several implementations), and abstract (so as to hide all details of the implementation).
3. For many efficient data structures access by position is important. In LEDA, we use an item concept to cast positions into an abstract form. We mention that most of the specifications given in the LEDA manual use this concept, i.e., the concept is adequate for the description of many data types.
4. LEDA contains efficient implementations for each of the data types, e.g., Fibonacci heaps for priority queues, skip lists and dynamic perfect hashing for dictionaries, ...
5. LEDA contains a comfortable data type graph. It offers the standard iterations such as ``for all nodes v of a graph G do'' or ``for all neighbors w of v do'', it allows to add and delete vertices and edges and it offers arrays and matrices indexed by nodes and edges,... The data type graph allows to write programs for graph problems in a form close to the typical text book presentation.
6. LEDA is implemented by a class library. It can be used with allmost any compiler (e.g., cfront2, cfront3, g++-1, g++-2, bcc, ztc).
7. LEDA is available by anonymous ftp from ftp.cs.uni-sb.de (134.96.7.254) /pub/LEDA The Distribution contains all sources, installation instructions, a technical report, and the LEDA user manual.
8. LEDA is not in the public domain, but can be used freely for research and teaching. A commercial license is available from the autor.
This manual contains the specifications of all data types and algorithms currently available in LEDA. Users should be familiar with the programming language (see [S91] or [L89]). The main concepts and some implementation details of LEDA are described in [MN89] and [N92]. The manual is structured as follows: In chapter one, which is a prerequisite for all other chapters, we discuss the basic concepts and notations used in LEDA. The other chapters define the data types and algorithms available in LEDA and give examples of their use. These chapters can be consulted independently from one another.
Version 3.0
The most important changes with respect to previous versions are a) Parameterized data types are realized by templates. In particular, declare macros used in previous versions are now obsolete and the syntax for a parameterized data type D with type parameters T1,..., Tk is DT1,..., Tk (cf. section 1.2). For compilers not supporting templates there is still a non-template variant (LEDA-N-3.0) available.
b) Arbitrary data types (not only pointer and simple types) can be used as actual type parameters (cf. section 1.2).
c) For many of the parameterized data types (in the current version: dictionary, priority queue, d_array, and sortseq) there exist variants taking an additional data structure parameter for choosing a particular implementation (cf. section 1.3).
d) The LEDA memory management system can be customized for user-defined classes (cf. section 7.3)
e) The efficiency of many data types and algorithms has been improved.
See also the ``Changes" file in the LEDA root directory.