master > master: code-rust - algorithmus sauberer + Kommentare
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@ -35,51 +35,48 @@ pub fn tarjan_algorithm<T>(gph: &Graph<T>, debug: bool) -> Vec<Vec<T>>
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let mut ctx = Context::new(&gph, debug);
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for u in gph.nodes.iter() {
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tarjan_visit(gph, u, &mut ctx);
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if ctx.get_state(&u) == State::UNTOUCHED {
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tarjan_visit(gph, &u, &mut ctx);
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}
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}
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return ctx.components;
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}
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/// recursive depth-first search algorithm to compute components
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fn tarjan_visit<T>(gph: &Graph<T>, v: &T, ctx: &mut Context<T>)
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/// Recursive depth-first search algorithm to compute strongly components of a graph.
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fn tarjan_visit<T>(gph: &Graph<T>, &u: &T, ctx: &mut Context<T>)
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where T: Eq + Hash + Clone + Copy + Display
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{
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// do nothing, if v already visited
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if !(ctx.get_state(v) == State::UNTOUCHED) { return; }
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// Place node on stack + initialise visit-index + component-index.
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ctx.max_index += 1;
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ctx.push(&u);
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ctx.set_root(&u, ctx.max_index);
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ctx.set_index(&u, ctx.max_index);
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ctx.set_state(&u, State::PENDING);
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/****************
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* First visit of v.
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* - Place v on stack.
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* - Initialise visit-index + component-index.
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* - After each rekursiv call, only those all
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* Compute strongly connected components of each child node.
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* NOTE: Child nodes remain on stack, if and only if parent is in same component.
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****************/
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ctx.max_index += 1;
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ctx.push(v);
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ctx.set_root(v, ctx.max_index);
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ctx.set_index(v, ctx.max_index);
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ctx.set_state(v, State::PENDING);
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// depth first search:
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for u in gph.successors(&v) {
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tarjan_visit(gph, &u, ctx);
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/****
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* u is in the same component as v, if and only if u is still on the stack.
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* In this case, update the associated component-index of v:
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****/
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if ctx.stack.contains(&u) {
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ctx.set_root(v, value_min!(ctx.get_root(v), ctx.get_root(&u)));
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for v in gph.successors(&u) {
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// Visit child node only if untouched:
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if ctx.get_state(&v) == State::UNTOUCHED {
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tarjan_visit(gph, &v, ctx);
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}
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// Update associated component-index of parent node, if in same component as child:
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if ctx.stack.contains(&v) {
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ctx.set_root(&u, value_min!(ctx.get_root(&u), ctx.get_root(&v)));
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}
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}
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ctx.set_state(v, State::FINISHED);
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ctx.log_info(&v);
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ctx.set_state(&u, State::FINISHED);
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ctx.log_info(&u);
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if ctx.get_index(v) == ctx.get_root(v) {
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if ctx.get_index(&u) == ctx.get_root(&u) {
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let mut component: Vec<T> = Vec::new();
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loop {
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let u = ctx.top();
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let v = ctx.top();
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ctx.pop();
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component.push(u.clone());
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if u == *v { break; }
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component.push(v.clone());
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if u == v { break; }
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}
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ctx.components.push(component);
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}
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