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[cpp] Clean up graph implementations

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This commit is contained in:
Shaun Reed
2022-04-13 21:15:03 -04:00
parent 6986c73651
commit 4b47630548
11 changed files with 227 additions and 185 deletions
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7
cpp/algorithms/graphs/weighted/graph.cpp
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@@ -1,8 +1,7 @@
/*##############################################################################
## Author: Shaun Reed ##
## Legal: All Content (c) 2021 Shaun Reed, all rights reserved ##
## About: An example of a weighted graph implementation ##
## Algorithms in this example are found in MIT Intro to Algorithms ##
## Legal: All Content (c) 2022 Shaun Reed, all rights reserved ##
## About: Driver program to test weighted graph implementation ##
## ##
## Contact: shaunrd0@gmail.com | URL: www.shaunreed.com | GitHub: shaunrd0 ##
################################################################################
@@ -105,7 +104,7 @@ int main (const int argc, const char * argv[])
// + Chapter 22, Figure 22.4 on DFS
// Unlike the simple-graph example, this final result matches MIT Algorithms
// + Aside from the placement of the watch node, which is not connected
// + This is because the node is visited after all other nodes are finished
// + This is because the node is visited after all other nodes are finished
std::vector<Node> order =
topologicalGraph.TopologicalSort(topologicalGraph.GetNodeCopy(6));
std::cout << "\nTopological order: ";

6
cpp/algorithms/graphs/weighted/lib-graph.cpp
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@@ -1,7 +1,8 @@
/*##############################################################################
## Author: Shaun Reed ##
## Legal: All Content (c) 2021 Shaun Reed, all rights reserved ##
## About: Driver program to test object graph implementation ##
## Legal: All Content (c) 2022 Shaun Reed, all rights reserved ##
## About: An example of a weighted graph implementation ##
## Algorithms in this example are found in MIT Intro to Algorithms ##
## ##
## Contact: shaunrd0@gmail.com | URL: www.shaunreed.com | GitHub: shaunrd0 ##
################################################################################
@@ -212,4 +213,3 @@ InfoMST Graph::KruskalMST() const
return searchInfo;
}

128
cpp/algorithms/graphs/weighted/lib-graph.hpp
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@@ -1,7 +1,7 @@
/*##############################################################################
## Author: Shaun Reed ##
## Legal: All Content (c) 2021 Shaun Reed, all rights reserved ##
## About: An example of an object graph implementation ##
## Legal: All Content (c) 2022 Shaun Reed, all rights reserved ##
## About: An example of a weighted graph implementation ##
## Algorithms in this example are found in MIT Intro to Algorithms ##
## ##
## Contact: shaunrd0@gmail.com | URL: www.shaunreed.com | GitHub: shaunrd0 ##
@@ -10,56 +10,14 @@
#ifndef LIB_GRAPH_HPP
#define LIB_GRAPH_HPP
#include <iostream>
#include <algorithm>
#include <iostream>
#include <map>
#include <queue>
#include <unordered_map>
#include <unordered_set>
#include <utility>
#include <vector>
#include <queue>
#include <unordered_set>
#include <unordered_map>
/******************************************************************************/
// Structures for tracking information gathered from various traversals
struct Node;
// Color represents the discovery status of any given node
// + White is undiscovered, Gray is in progress, Black is fully discovered
enum Color {White, Gray, Black};
// Information used in all searches
struct SearchInfo {
// Coloring of the nodes is used in both DFS and BFS
Color discovered = White;
};
// Information that is only used in BFS
struct BFS : SearchInfo {
// Used to represent distance from start node
int distance = 0;
// Used to represent the parent node that discovered this node
// + If we use this node as the starting point, this will remain a nullptr
const Node *predecessor = nullptr;
};
// Information that is only used in DFS
struct DFS : SearchInfo {
// Create a pair to track discovery / finish time
// + Discovery time is the iteration the node is first discovered
// + Finish time is the iteration the node has been checked completely
// ++ A finished node has considered all adjacent nodes
std::pair<int, int> discoveryFinish;
};
struct MST : SearchInfo {
int32_t parent = INT32_MIN;
int rank = 0;
};
// Store search information in unordered_maps so we can pass it around easily
// + Allows each node to store relative information on the traversal
using InfoBFS = std::unordered_map<int, struct BFS>;
using InfoDFS = std::unordered_map<int, struct DFS>;
/******************************************************************************/
@@ -69,7 +27,8 @@ struct Node {
public:
// Constructors
Node(const Node &rhs) = default;
Node & operator=(Node rhs) {
Node & operator=(Node rhs)
{
if (this == &rhs) return *this;
swap(*this, rhs);
return *this;
@@ -80,7 +39,8 @@ public:
for (const auto &i : adj) adjacent.emplace(i.first, i.second);
}
friend void swap(Node &a, Node &b) {
friend void swap(Node &a, Node &b)
{
std::swap(a.number, b.number);
std::swap(a.adjacent, b.adjacent);
}
@@ -95,10 +55,71 @@ public:
bool operator!=(const Node &b) const { return this->number != b.number;}
};
/******************************************************************************/
// Base struct for storing traversal information on all nodes
// Color represents the discovery status of any given node
enum Color {
// Node is marked as undiscovered
White,
// Node discovery is in progress; Some adjacent nodes have not been checked
Gray,
// Node has been discovered; All adjacent nodes have been checked
Black
};
// Information used in all searches
struct SearchInfo {
// Coloring of the nodes is used in both DFS and BFS
Color discovered = White;
};
/******************************************************************************/
// BFS search information struct
// Information that is only used in BFS
struct BFS : SearchInfo {
// Used to represent distance from start node
int distance = 0;
// Used to represent the parent node that discovered this node
// + If we use this node as the starting point, this will remain a nullptr
const Node *predecessor = nullptr;
};
// Store search information in unordered_maps so we can pass it around easily
// + Allows each node to store relative information on the traversal
using InfoBFS = std::unordered_map<int, struct BFS>;
/******************************************************************************/
// DFS search information struct
// Information that is only used in DFS
struct DFS : SearchInfo {
// Create a pair to track discovery / finish time
// + Discovery time is the iteration the node is first discovered
// + Finish time is the iteration the node has been checked completely
// ++ A finished node has considered all adjacent nodes
std::pair<int, int> discoveryFinish;
};
/******************************************************************************/
// MST search information struct
struct MST : SearchInfo {
int32_t parent = INT32_MIN;
int rank = 0;
};
using InfoDFS = std::unordered_map<int, struct DFS>;
using Edges = std::multimap<int, std::pair<int, int>>;
struct InfoMST {
explicit InfoMST(const std::vector<Node> &nodes) {
for (const auto &node : nodes){
explicit InfoMST(const std::vector<Node> &nodes)
{
for (const auto &node : nodes) {
// Initialize the default values for forest tracked by this struct
// + This data is used in KruskalMST() to find the MST
MakeSet(node.number);
@@ -154,11 +175,12 @@ struct InfoMST {
}
return searchInfo[x].parent;
}
};
/******************************************************************************/
// Graph class declaration
class Graph {
public:
// Constructor