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Added topological sorting algorithms #1677
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74e8ec2
feat:added kanns algorithm
9f3aa64
Updated kahn's algorithm
2f2c099
Updated kahn's algorithm
3e9c9e4
feat: added topological sorting algorithm
RaviSadam f0325a5
Merge remote-tracking branch 'origin/master'
RaviSadam 99535c5
Delete Graphs/KahnsAlgorithm.js
RaviSadam 35fe1c3
Delete Graphs/KannsAlgorithm.js
RaviSadam ef63f66
Delete Graphs/test/KahnsAlgorithm.test.js
RaviSadam 154a330
Delete Graphs/test/KannsAlgorithm.test.js
RaviSadam 191993f
Merge remote-tracking branch 'origin/master'
RaviSadam f252873
feat:added topological sorting algorithms
RaviSadam c179e51
Updated Topo Sort
RaviSadam 8eb4bda
Merge branch 'main' of https://github.com/RaviSadam/JavaScript
RaviSadam b2c3d6d
updated topological sort
RaviSadam 19d0d8f
updated topological sort
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import Queue from '../Data-Structures/Queue/Queue' | ||
/** | ||
* @author {RaviSadam} | ||
* @name TopoSortIterative | ||
* @description - | ||
* Topological sorting algorithm implementation in JavaScript(Khan's Algorithm) | ||
* @summary | ||
* Topological sorting for Directed Acyclic Graph is a linear ordering of vertices | ||
* such that for every directed edge u-v, vertex u comes before v in the ordering. | ||
* | ||
* @param graph - Graph (adjacency list) | ||
* @returns {Array} - Gives null if graph has cycle otherwise result array | ||
* | ||
*/ | ||
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export function TopoSortIterative(graph) { | ||
const n = graph.length | ||
const inDegree = Array(n).fill(0) | ||
const queue = new Queue() | ||
const result = Array(n).fill(0) | ||
let index = 0 | ||
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for (const neighbors of graph) { | ||
for (const neighbor of neighbors) { | ||
inDegree[neighbor] += 1 | ||
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} | ||
} | ||
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for (let i = 0; i < n; i++) { | ||
if (inDegree[i] === 0) { | ||
queue.enqueue(i) | ||
} | ||
} | ||
while (queue.length !== 0) { | ||
const node = queue.dequeue() | ||
result[index] = node | ||
index += 1 | ||
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for (let neighbor of graph[node]) { | ||
inDegree[neighbor] -= 1 | ||
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if (inDegree[neighbor] === 0) { | ||
queue.enqueue(neighbor) | ||
} | ||
} | ||
} | ||
if (index !== n) return null | ||
return result | ||
} |
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function TopoSortRecursiveFunction(graph, visited, stack, path, vertex) { | ||
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//marking current vertex as visited | ||
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visited.add(vertex) | ||
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//marking current vertex as being part of current path | ||
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path[vertex] = 1 | ||
if (graph[vertex] && graph[vertex].length !== 0) { | ||
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for (const neighbor of graph[vertex]) { | ||
//if neighbor is not visited then visit else continue | ||
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if (!visited.has(neighbor)) { | ||
TopoSortRecursiveFunction(graph, visited, stack, path, neighbor) | ||
} else if (path[neighbor] == 1) return | ||
} | ||
} | ||
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//unmarking vertex | ||
path[vertex] = 0 | ||
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//visited all vertex coming after the current vertex | ||
//so added to stack | ||
stack.push(vertex) | ||
} | ||
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/** | ||
* | ||
* @author {RaviSadam} | ||
* @name TopoSortRecursive | ||
* @description - | ||
* Topological sorting algorithm implementation in JavaScript | ||
* @summary | ||
* Topological sorting for Directed Acyclic Graph is a linear ordering of vertices | ||
* such that for every directed edge u-v, vertex u comes before v in the ordering. | ||
* | ||
* @param graph - Graph (adjacency list) | ||
* @returns {Array} - Gives null if graph has cycle otherwise result array | ||
* | ||
*/ | ||
export function TopoSortRecursive(graph) { | ||
const n = graph.length | ||
const stack = [] | ||
//visited set for keep tracking of visited vertises | ||
const visited = new Set() | ||
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//path array for keep tacking of vertices | ||
//visited in current path | ||
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const path = Array(n).fill(0) | ||
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for (let i = 0; i < n; i++) { | ||
if (!visited.has(i)) { | ||
TopoSortRecursiveFunction(graph, visited, stack, path, i) | ||
} | ||
} | ||
for (const value of path) { | ||
if (value === 1) return null | ||
} | ||
//reverse the stack for getting exact topological order | ||
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stack.reverse() | ||
return stack | ||
} |
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Original file line number | Diff line number | Diff line change |
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import { TopoSortIterative } from '../TopoSortIterative' | ||
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describe('Iterative Topological Sorting', () => { | ||
test('Graph without cycle', () => { | ||
const graph = [[], [], [3], [1], [0, 1], [0, 2]] | ||
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expect(TopoSortIterative(graph, 6)).toEqual([4, 5, 0, 2, 3, 1]) | ||
}) | ||
test('Graph with cycle', () => { | ||
const graph = [[2], [], [3, 5], [0, 1], [0, 2]] | ||
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expect(TopoSortIterative(graph, 6)).toBe(null) | ||
}) | ||
}) |
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Original file line number | Diff line number | Diff line change |
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@@ -0,0 +1,18 @@ | ||
import { TopoSortRecursive } from '../TopoSortRecursive' | ||
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describe('Recursive Topological Sorting', () => { | ||
test('Graph without cycle', () => { | ||
const graph = [[], [], [3], [1], [0, 1], [0, 2]] | ||
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expect(TopoSortRecursive(graph, 6)).toEqual([5, 4, 2, 3, 1, 0]) | ||
}) | ||
test('Graph with cycle', () => { | ||
const graph = [[2], [], [3, 5], [0, 1], [0, 2]] | ||
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expect(TopoSortRecursive(graph, 6)).toBe(null) | ||
}) | ||
test('Graph with disconnected components', () => { | ||
const graph = [[1, 2], [3], [3], [], [5], []] | ||
expect(TopoSortRecursive(graph, 6)).toEqual([4, 5, 0, 2, 1, 3]) | ||
}) | ||
}) |
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