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let hopcroftTarjanBiconnected = function() {
let eles = this;
let nodes = {};
let id = 0;
let edgeCount = 0;
let components = [];
let stack = [];
let visitedEdges = {};
const buildComponent = (x, y) => {
let i = stack.length-1;
let cutset = [];
let component = eles.spawn();
while (stack[i].x != x || stack[i].y != y) {
cutset.push(stack.pop().edge);
i--;
}
cutset.push(stack.pop().edge);
cutset.forEach(edge => {
let connectedNodes = edge.connectedNodes()
.intersection(eles);
component.merge(edge);
connectedNodes.forEach(node => {
const nodeId = node.id();
const connectedEdges = node.connectedEdges()
.intersection(eles);
component.merge(node);
if (!nodes[nodeId].cutVertex) {
component.merge(connectedEdges);
} else {
component.merge(connectedEdges.filter(edge => edge.isLoop()));
}
});
});
components.push(component);
};
const biconnectedSearch = (root, currentNode, parent) => {
if (root === parent) edgeCount += 1;
nodes[currentNode] = {
id : id,
low : id++,
cutVertex : false
};
let edges = eles.getElementById(currentNode)
.connectedEdges()
.intersection(eles);
if (edges.size() === 0) {
components.push(eles.spawn(eles.getElementById(currentNode)));
} else {
let sourceId, targetId, otherNodeId, edgeId;
edges.forEach(edge => {
sourceId = edge.source().id();
targetId = edge.target().id();
otherNodeId = (sourceId === currentNode) ? targetId : sourceId;
if (otherNodeId !== parent) {
edgeId = edge.id();
if (!visitedEdges[edgeId]) {
visitedEdges[edgeId] = true;
stack.push({
x : currentNode,
y : otherNodeId,
edge
});
}
if (!(otherNodeId in nodes)) {
biconnectedSearch(root, otherNodeId, currentNode);
nodes[currentNode].low = Math.min(nodes[currentNode].low,
nodes[otherNodeId].low);
if (nodes[currentNode].id <= nodes[otherNodeId].low) {
nodes[currentNode].cutVertex = true;
buildComponent(currentNode, otherNodeId);
}
} else {
nodes[currentNode].low = Math.min(nodes[currentNode].low,
nodes[otherNodeId].id);
}
}
});
}
};
eles.forEach(ele => {
if (ele.isNode()) {
let nodeId = ele.id();
if (!(nodeId in nodes)) {
edgeCount = 0;
biconnectedSearch(nodeId, nodeId);
nodes[nodeId].cutVertex = (edgeCount > 1);
}
}
});
let cutVertices = Object.keys(nodes)
.filter(id => nodes[id].cutVertex)
.map(id => eles.getElementById(id));
return {
cut: eles.spawn(cutVertices),
components
};
};
export default {
hopcroftTarjanBiconnected,
htbc: hopcroftTarjanBiconnected,
htb: hopcroftTarjanBiconnected,
hopcroftTarjanBiconnectedComponents: hopcroftTarjanBiconnected
};
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