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Add detect cycle.

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This commit is contained in:
Oleksii Trekhleb 2018-05-05 10:58:04 +03:00
parent 20bc442dcf
commit d0504fdbb0
4 changed files with 93 additions and 24 deletions
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3
.eslintrc
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@ -9,6 +9,7 @@
"no-bitwise": "off",
"no-lonely-if": "off",
"class-methods-use-this": "off",
"arrow-body-style": "off"
"arrow-body-style": "off",
"no-loop-func": "off"
}
}

72
src/algorithms/graph/breadth-first-search/__test__/breadthFirstSearch.test.js
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@ -54,8 +54,39 @@ describe('breadthFirstSearch', () => {
expect(enterVertexCallback).toHaveBeenCalledTimes(8);
expect(leaveVertexCallback).toHaveBeenCalledTimes(8);
expect(enterVertexCallback.mock.calls.toString()).toBe('A,B,D,E,C,H,F,G');
expect(leaveVertexCallback.mock.calls.toString()).toBe('A,B,D,E,C,H,F,G');
const enterVertexParamsMap = [
{ currentVertex: vertexA, previousVertex: null },
{ currentVertex: vertexB, previousVertex: vertexA },
{ currentVertex: vertexD, previousVertex: vertexB },
{ currentVertex: vertexE, previousVertex: vertexD },
{ currentVertex: vertexC, previousVertex: vertexE },
{ currentVertex: vertexH, previousVertex: vertexC },
{ currentVertex: vertexF, previousVertex: vertexH },
{ currentVertex: vertexG, previousVertex: vertexF },
];
for (let callIndex = 0; callIndex < graph.getAllVertices().length; callIndex += 1) {
const params = enterVertexCallback.mock.calls[callIndex][0];
expect(params.currentVertex).toEqual(enterVertexParamsMap[callIndex].currentVertex);
expect(params.previousVertex).toEqual(enterVertexParamsMap[callIndex].previousVertex);
}
const leaveVertexParamsMap = [
{ currentVertex: vertexA, previousVertex: null },
{ currentVertex: vertexB, previousVertex: vertexA },
{ currentVertex: vertexD, previousVertex: vertexB },
{ currentVertex: vertexE, previousVertex: vertexD },
{ currentVertex: vertexC, previousVertex: vertexE },
{ currentVertex: vertexH, previousVertex: vertexC },
{ currentVertex: vertexF, previousVertex: vertexH },
{ currentVertex: vertexG, previousVertex: vertexF },
];
for (let callIndex = 0; callIndex < graph.getAllVertices().length; callIndex += 1) {
const params = leaveVertexCallback.mock.calls[callIndex][0];
expect(params.currentVertex).toEqual(leaveVertexParamsMap[callIndex].currentVertex);
expect(params.previousVertex).toEqual(leaveVertexParamsMap[callIndex].previousVertex);
}
});
it('should allow to create custom vertex visiting logic', () => {
@ -100,15 +131,44 @@ describe('breadthFirstSearch', () => {
breadthFirstSearch(graph, vertexA, {
enterVertex: enterVertexCallback,
leaveVertex: leaveVertexCallback,
allowTraversal: (vertex, neighbor) => {
return !(vertex === vertexA && neighbor === vertexB);
allowTraversal: ({ currentVertex, nextVertex }) => {
return !(currentVertex === vertexA && nextVertex === vertexB);
},
});
expect(enterVertexCallback).toHaveBeenCalledTimes(7);
expect(leaveVertexCallback).toHaveBeenCalledTimes(7);
expect(enterVertexCallback.mock.calls.toString()).toBe('A,D,E,H,F,D,H');
expect(leaveVertexCallback.mock.calls.toString()).toBe('A,D,E,H,F,D,H');
const enterVertexParamsMap = [
{ currentVertex: vertexA, previousVertex: null },
{ currentVertex: vertexD, previousVertex: vertexA },
{ currentVertex: vertexE, previousVertex: vertexD },
{ currentVertex: vertexH, previousVertex: vertexE },
{ currentVertex: vertexF, previousVertex: vertexH },
{ currentVertex: vertexD, previousVertex: vertexF },
{ currentVertex: vertexH, previousVertex: vertexD },
];
for (let callIndex = 0; callIndex < 7; callIndex += 1) {
const params = enterVertexCallback.mock.calls[callIndex][0];
expect(params.currentVertex).toEqual(enterVertexParamsMap[callIndex].currentVertex);
expect(params.previousVertex).toEqual(enterVertexParamsMap[callIndex].previousVertex);
}
const leaveVertexParamsMap = [
{ currentVertex: vertexA, previousVertex: null },
{ currentVertex: vertexD, previousVertex: vertexA },
{ currentVertex: vertexE, previousVertex: vertexD },
{ currentVertex: vertexH, previousVertex: vertexE },
{ currentVertex: vertexF, previousVertex: vertexH },
{ currentVertex: vertexD, previousVertex: vertexF },
{ currentVertex: vertexH, previousVertex: vertexD },
];
for (let callIndex = 0; callIndex < 7; callIndex += 1) {
const params = leaveVertexCallback.mock.calls[callIndex][0];
expect(params.currentVertex).toEqual(leaveVertexParamsMap[callIndex].currentVertex);
expect(params.previousVertex).toEqual(leaveVertexParamsMap[callIndex].previousVertex);
}
});
});

30
src/algorithms/graph/breadth-first-search/breadthFirstSearch.js
View File

@ -2,11 +2,14 @@ import Queue from '../../../data-structures/queue/Queue';
/**
* @typedef {Object} Callbacks
* @property {function(vertex: GraphVertex, neighbor: GraphVertex): boolean} allowTraversal -
*
* @property {function(vertices: Object): boolean} [allowTraversal] -
* Determines whether DFS should traverse from the vertex to its neighbor
* (along the edge). By default prohibits visiting the same vertex again.
* @property {function(vertex: GraphVertex)} enterVertex - Called when DFS enters the vertex.
* @property {function(vertex: GraphVertex)} leaveVertex - Called when DFS leaves the vertex.
*
* @property {function(vertices: Object)} [enterVertex] - Called when BFS enters the vertex.
*
* @property {function(vertices: Object)} [leaveVertex] - Called when BFS leaves the vertex.
*/
/**
@ -21,9 +24,9 @@ function initCallbacks(callbacks = {}) {
const allowTraversalCallback = (
() => {
const seen = {};
return (vertex, neighbor) => {
if (!seen[neighbor.getKey()]) {
seen[neighbor.getKey()] = true;
return ({ nextVertex }) => {
if (!seen[nextVertex.getKey()]) {
seen[nextVertex.getKey()] = true;
return true;
}
return false;
@ -50,18 +53,23 @@ export default function breadthFirstSearch(graph, startVertex, originalCallbacks
// Do initial queue setup.
vertexQueue.enqueue(startVertex);
let previousVertex = null;
// Traverse all vertices from the queue.
while (!vertexQueue.isEmpty()) {
const currentVertex = vertexQueue.dequeue();
callbacks.enterVertex(currentVertex);
callbacks.enterVertex({ currentVertex, previousVertex });
// Add all neighbors to the queue for future traversals.
graph.getNeighbors(currentVertex).forEach((neighbor) => {
if (callbacks.allowTraversal(currentVertex, neighbor)) {
vertexQueue.enqueue(neighbor);
graph.getNeighbors(currentVertex).forEach((nextVertex) => {
if (callbacks.allowTraversal({ previousVertex, currentVertex, nextVertex })) {
vertexQueue.enqueue(nextVertex);
}
});
callbacks.leaveVertex(currentVertex);
callbacks.leaveVertex({ currentVertex, previousVertex });
// Memorize current vertex before next loop.
previousVertex = currentVertex;
}
}

12
src/algorithms/graph/depth-first-search/__test__/depthFirstSearch.test.js
View File

@ -67,7 +67,7 @@ describe('depthFirstSearch', () => {
expect(params.previousVertex).toEqual(enterVertexParamsMap[callIndex].previousVertex);
}
const leavingVertexParamsMap = [
const leaveVertexParamsMap = [
{ currentVertex: vertexG, previousVertex: vertexC },
{ currentVertex: vertexC, previousVertex: vertexB },
{ currentVertex: vertexB, previousVertex: vertexA },
@ -79,8 +79,8 @@ describe('depthFirstSearch', () => {
for (let callIndex = 0; callIndex < graph.getAllVertices().length; callIndex += 1) {
const params = leaveVertexCallback.mock.calls[callIndex][0];
expect(params.currentVertex).toEqual(leavingVertexParamsMap[callIndex].currentVertex);
expect(params.previousVertex).toEqual(leavingVertexParamsMap[callIndex].previousVertex);
expect(params.currentVertex).toEqual(leaveVertexParamsMap[callIndex].currentVertex);
expect(params.previousVertex).toEqual(leaveVertexParamsMap[callIndex].previousVertex);
}
});
@ -146,7 +146,7 @@ describe('depthFirstSearch', () => {
expect(params.previousVertex).toEqual(enterVertexParamsMap[callIndex].previousVertex);
}
const leavingVertexParamsMap = [
const leaveVertexParamsMap = [
{ currentVertex: vertexG, previousVertex: vertexD },
{ currentVertex: vertexD, previousVertex: vertexA },
{ currentVertex: vertexG, previousVertex: vertexD },
@ -158,8 +158,8 @@ describe('depthFirstSearch', () => {
for (let callIndex = 0; callIndex < graph.getAllVertices().length; callIndex += 1) {
const params = leaveVertexCallback.mock.calls[callIndex][0];
expect(params.currentVertex).toEqual(leavingVertexParamsMap[callIndex].currentVertex);
expect(params.previousVertex).toEqual(leavingVertexParamsMap[callIndex].previousVertex);
expect(params.currentVertex).toEqual(leaveVertexParamsMap[callIndex].currentVertex);
expect(params.previousVertex).toEqual(leaveVertexParamsMap[callIndex].previousVertex);
}
});
});