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Added Connected Components using DFS #223

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Merged
itsvinayak merged 1 commit into from
Jul 7, 2020
Merged

Added Connected Components using DFS #223

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56 changes: 56 additions & 0 deletions Graphs/ConnectedComponents.js
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Original file line number Diff line number Diff line change
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class GraphUnweightedUndirected {
// Unweighted Undirected Graph class
constructor () {
this.connections = {}
}

addNode (node) {
// Function to add a node to the graph (connection represented by set)
this.connections[node] = new Set()
}

addEdge (node1, node2) {
// Function to add an edge (adds the node too if they are not present in the graph)
if (!(node1 in this.connections)) { this.addNode(node1) }
if (!(node2 in this.connections)) { this.addNode(node2) }
this.connections[node1].add(node2)
this.connections[node2].add(node1)
}

DFSComponent (components, node, visited) {
// Helper function to populate the visited set with the nodes in each component

// adding the first visited node in the component to the array
components.push(node)
const stack = [node]
// populating the visited set using DFS (Iterative)
while (stack.length > 0) {
const curr = stack.pop()
visited.add(curr.toString())
for (const neighbour of this.connections[curr].keys()) {
if (!visited.has(neighbour.toString())) { stack.push(neighbour) }
}
}
}

connectedComponents () {
// Function to generate the Connected Components
// Result is an array containing 1 node from each component
const visited = new Set()
const components = []
for (const node of Object.keys(this.connections)) {
if (!visited.has(node.toString())) { this.DFSComponent(components, node, visited) }
}
return components
}
}

function main () {
const graph = new GraphUnweightedUndirected()
graph.addEdge(1, 2) // Component 1
graph.addEdge(3, 4) // Component 2
graph.addEdge(3, 5) // Component 2
console.log(graph.connectedComponents())
}

main()