Find maximum weight cycle in an undirected graph in node js
Js program for Find maximum weight cycle in an undirected graph. Here problem description and explanation.
/*
Node JS program for
Maximum weight cycle in an undirected graph
*/
class AjlistNode
{
constructor(id, weight)
{
// Set value of node key
this.id = id;
this.weight = weight;
this.next = null;
}
}
class Vertices
{
constructor(data)
{
this.data = data;
this.next = null;
this.last = null;
}
}
class Graph
{
constructor(size)
{
// Set value
this.size = size;
this.result = 0;
this.node = Array(size).fill(null);
this.setData();
}
// Set initial node value
setData()
{
if (this.size <= 0)
{
console.log("\nEmpty Graph");
}
else
{
for (var index = 0; index < this.size; index++)
{
// Set initial node value
this.node[index] = new Vertices(index);
}
}
}
connection(start, last, weight)
{
// Safe connection
var edge = new AjlistNode(last, weight);
if (this.node[start].next == null)
{
this.node[start].next = edge;
}
else
{
// Add edge at the end
this.node[start].last.next = edge;
}
// Get last edge
this.node[start].last = edge;
}
// Handling the request of adding new edge
addEdge(start, last, weight)
{
if (start >= 0 && start < this.size &&
last >= 0 && last < this.size)
{
this.connection(start, last, weight);
if (start == last)
{
return;
}
this.connection(last, start, weight);
}
else
{
// When invalid nodes
console.log("\nHere Something Wrong");
}
}
printGraph()
{
if (this.size > 0)
{
// Print graph ajlist Node value
for (var index = 0; index < this.size; ++index)
{
process.stdout.write("\nAdjacency list of vertex " +
index + " :");
var edge = this.node[index].next;
while (edge != null)
{
// Display graph node
process.stdout.write(" " +
this.node[edge.id].data + "[" + edge.weight + "]");
// Visit to next edge
edge = edge.next;
}
}
}
}
maximumCycle(start, last, visit, sum)
{
if (start >= this.size || last >= this.size ||
start < 0 || last < 0 || this.size <= 0)
{
return;
}
if (visit[start] == true)
{
if (start == last && sum > this.result)
{
// When find a new max weight cycle
this.result = sum;
}
return;
}
// Here modified the value of visited node
visit[start] = true;
// This is used to iterate nodes edges
var edge = this.node[start].next;
while (edge != null)
{
this.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;
}
maxWeightCycle()
{
if (this.size <= 0)
{
// Empty graph
return;
}
// Auxiliary space which is used to store
// information about visited node
var visit = Array(this.size).fill(false);
this.result = -Number.MAX_VALUE;
for (var i = 0; i < this.size; ++i)
{
// Check cycle of node i to i
// Here initial cycle weight is zero
this.maximumCycle(i, i, visit, 0);
}
if (this.result == -Number.MAX_VALUE)
{
console.log("\nMax weight cycle : None ");
}
else
{
console.log("\nMax weight cycle : " + this.result);
}
}
}
function main()
{
// 6 implies the number of nodes in graph
var g = new Graph(6);
// Connect node with an edge
// First and second parameter indicate node
// Last parameter is indicate weight
g.addEdge(0, 1, 3);
g.addEdge(0, 3, -3);
g.addEdge(0, 4, 7);
g.addEdge(0, 5, 1);
g.addEdge(1, 2, 11);
g.addEdge(1, 4, 8);
g.addEdge(1, 5, 0);
g.addEdge(2, 3, 1);
g.addEdge(2, 5, 5);
g.addEdge(3, 4, 2);
g.addEdge(4, 5, 8);
// Print graph element
g.printGraph();
// Test
g.maxWeightCycle();
}
// Start program execution
main();
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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