Find maximum weight cycle in an undirected graph in swift

Swift program for Find maximum weight cycle in an undirected graph. Here more information.

``````import Foundation
/*
Swift 4 program for
Maximum weight cycle in an undirected graph
*/
class AjlistNode
{
// Vertices node key
var id: Int;
var weight: Int;
var next: AjlistNode? ;
init(_ id: Int, _ weight: Int)
{
// Set value of node key
self.id = id;
self.weight = weight;
self.next = nil;
}
}
class Vertices
{
var data: Int;
var next: AjlistNode? ;
var last: AjlistNode? ;
init(_ data: Int)
{
self.data = data;
self.next = nil;
self.last = nil;
}
}
class Graph
{
// Number of Vertices
var size: Int;
var result: Int;
var node: [Vertices? ];
init(_ size: Int)
{
// Set value
self.size = size;
self.result = 0;
self.node = Array(repeating: nil, count: size);
self.setData();
}
// Set initial node value
func setData()
{
if (self.size <= 0)
{
print("\nEmpty Graph");
}
else
{
var index: Int = 0;
while (index < self.size)
{
// Set initial node value
self.node[index] = Vertices(index);
index += 1;
}
}
}
func connection(_ start: Int, _ last: Int, _ weight: Int)
{
// Safe connection
let edge: AjlistNode? = AjlistNode(last, weight);
if (self.node[start]!.next == nil)
{
self.node[start]!.next = edge;
}
else
{
// Add edge at the end
self.node[start]!.last!.next = edge;
}
// Get last edge
self.node[start]!.last = edge;
}
//  Handling the request of adding new edge
func addEdge(_ start: Int, _ last: Int, _ weight: Int)
{
if (start >= 0 && start < self.size &&
last >= 0 && last < self.size)
{
self.connection(start, last, weight);
if (start == last)
{
return;
}
self.connection(last, start, weight);
}
else
{
// When invalid nodes
print("\nHere Something Wrong");
}
}
func printGraph()
{
if (self.size > 0)
{
var index: Int = 0;
// Print graph ajlist Node value
while (index < self.size)
{
print("\nAdjacency list of vertex " +
String(index) + " :", terminator: "");
var edge: AjlistNode? = self.node[index]!.next;
while (edge  != nil)
{
// Display graph node
print("  " + String(self.node[edge!.id]!.data) +
"[" + String(edge!.weight) + "]", terminator: "");
// Visit to next edge
edge = edge!.next;
}
index += 1;
}
}
}
func maximumCycle(_ start: Int, _ last: Int,
_ visit: inout[Bool], _ sum: Int)
{
if (start >= self.size || last >= self.size ||
start < 0 || last < 0 || self.size <= 0)
{
return;
}
if (visit[start] == true)
{
if (start == last && sum > self.result)
{
// When find a new max weight cycle
self.result = sum;
}
return;
}
// Here modified  the value of visited node
visit[start] = true;
// This is used to iterate nodes edges
var edge: AjlistNode? = self.node[start]!.next;
while (edge  != nil)
{
self.maximumCycle(edge!.id, last,
&visit, sum + (edge!.weight));
// Visit to next edge
edge = edge!.next;
}
// Reset the value of visited node status
visit[start] = false;
}
func maxWeightCycle()
{
if (self.size <= 0)
{
// Empty graph
return;
}
// Auxiliary space which is used to store
var visit: [Bool] = Array(repeating: false, count: self.size);
self.result = Int.min;
var i: Int = 0;
while (i < self.size)
{
// Check cycle of node i to i
// Here initial cycle weight is zero
self.maximumCycle(i, i, &visit, 0);
i += 1;
}
if (self.result == Int.min)
{
print("\nMax weight cycle : None ");
}
else
{
print("\nMax weight cycle : " + String(self.result));
}
}
static func main(_ args: [String])
{
// 6 implies the number of nodes in graph
let g: Graph = Graph(6);
// Connect node with an edge
// First and second parameter indicate node
// Last parameter is indicate weight
// Print graph element
g.printGraph();
// Test
g.maxWeightCycle();
}
}
Graph.main([String]());``````

Output

``````Adjacency list of vertex 0 :  1[3]  3[-3]  4[7]  5[1]
Adjacency list of vertex 1 :  0[3]  2[11]  4[8]  5[0]
Adjacency list of vertex 2 :  1[11]  3[1]  5[5]
Adjacency list of vertex 3 :  0[-3]  2[1]  4[2]
Adjacency list of vertex 4 :  0[7]  1[8]  3[2]  5[8]
Adjacency list of vertex 5 :  0[1]  1[0]  2[5]  4[8]
Max weight cycle : 34``````

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