144 lines
4.8 KiB
C++
144 lines
4.8 KiB
C++
/*##############################################################################
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## Author: Shaun Reed ##
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## Legal: All Content (c) 2022 Shaun Reed, all rights reserved ##
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## About: An example of an object graph implementation ##
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## Algorithms in this example are found in MIT Intro to Algorithms ##
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## ##
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## Contact: shaunrd0@gmail.com | URL: www.shaunreed.com | GitHub: shaunrd0 ##
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################################################################################
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*/
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#ifndef LIB_GRAPH_HPP
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#define LIB_GRAPH_HPP
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#include <algorithm>
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#include <iostream>
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#include <map>
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#include <queue>
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#include <unordered_map>
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#include <unordered_set>
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#include <utility>
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#include <vector>
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/******************************************************************************/
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// Node structure for representing a graph
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struct Node {
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public:
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// Constructors
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Node(const Node &rhs) = default;
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Node & operator=(Node rhs)
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{
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if (this == &rhs) return *this;
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swap(*this, rhs);
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return *this;
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}
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Node(int num, std::vector<int> adj) : number(num), adjacent(std::move(adj)) {}
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friend void swap(Node &a, Node &b)
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{
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std::swap(a.number, b.number);
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std::swap(a.adjacent, b.adjacent);
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}
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int number;
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std::vector<int> adjacent;
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// Define operator== for std::find; And comparisons between nodes
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bool operator==(const Node &b) const { return this->number == b.number;}
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// Define an operator!= for comparing nodes for inequality
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bool operator!=(const Node &b) const { return this->number != b.number;}
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};
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/******************************************************************************/
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// Base struct for storing traversal information on all nodes
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// Color represents the discovery status of any given node
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enum Color {
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// Node is marked as undiscovered
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White,
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// Node discovery is in progress; Some adjacent nodes have not been checked
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Gray,
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// Node has been discovered; All adjacent nodes have been checked
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Black
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};
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// Information used in all searches tracked for each node
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struct NodeInfo {
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// Coloring of the nodes is used in both DFS and BFS
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Color discovered = White;
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};
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/******************************************************************************/
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// BFS search information struct
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// Node information that is only used in BFS
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struct BFS : NodeInfo {
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// Used to represent distance from start node
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int distance = 0;
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// Used to represent the parent node that discovered this node
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// + If we use this node as the starting point, this will remain a nullptr
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const Node *predecessor = nullptr;
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};
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// Store search information in unordered_maps so we can pass it around easily
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// + Allows each node to store relative information on the traversal
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using InfoBFS = std::unordered_map<int, struct BFS>;
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/******************************************************************************/
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// DFS search information struct
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// Node information that is only used in DFS
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struct DFS : NodeInfo {
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// Create a pair to track discovery / finish time
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// + Discovery time is the iteration the node is first discovered
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// + Finish time is the iteration the node has been checked completely
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// ++ A finished node has considered all adjacent nodes
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std::pair<int, int> discoveryFinish;
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};
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using InfoDFS = std::unordered_map<int, struct DFS>;
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/******************************************************************************/
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// Graph class declaration
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class Graph {
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public:
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// Constructor
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explicit Graph(std::vector<Node> nodes) : nodes_(std::move(nodes)) {}
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// Breadth First Search
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InfoBFS BFS(const Node& startNode) const;
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std::deque<Node> PathBFS(const Node &start, const Node &finish) const;
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// Depth First Search
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InfoDFS DFS() const;
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// An alternate DFS that checks each node of the graph beginning at startNode
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InfoDFS DFS(const Node &startNode) const;
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// Visit function is used in both versions of DFS
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void DFSVisit(int &time, const Node& startNode, InfoDFS &dfs) const;
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// Topological sort, using DFS
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std::vector<Node> TopologicalSort(const Node &startNode) const;
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// Returns a copy of a node with the number i within the graph
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// + This uses the private, non-const accessor GetNode() and returns a copy
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inline Node GetNodeCopy(int i) { return GetNode(i);}
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// Return a constant iterator for reading node values
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inline std::vector<Node>::const_iterator NodeBegin() { return nodes_.cbegin();}
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private:
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// A non-const accessor for direct access to a node with the number value i
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inline Node & GetNode(int i)
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{ return *std::find(nodes_.begin(), nodes_.end(), Node(i, {}));}
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// For grabbing a const qualified node
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inline const Node & GetNode(int i) const
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{ return *std::find(nodes_.begin(), nodes_.end(), Node(i, {}));}
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std::vector<Node> nodes_;
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};
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#endif // LIB_GRAPH_HPP
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