shithub: asif

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pheap: fix decreasekey dropping entire branch

--- a/pheap.c

+++ b/pheap.c

@@ -91,6 +91,7 @@

 	p = *queue;

 	if(p == nil)

 		return nil;

+	dprint(Logtrace, "pheap::popqueue %#p %.6f\n", p, p->n);

 	*queue = mergepairs(p->left);

 	return p;

 }

@@ -98,9 +99,19 @@

 void

 decreasekey(Pairheap *p, double Δ, Pairheap **queue)

 {

+	Pairheap *q;

+

+	dprint(Logtrace, "pheap::decreasekey %#p %.6f Δ %.6f\n", p, p->n, Δ);

 	p->n -= Δ;

 	if(p->parent != nil && p->n < p->parent->n){

-		p->parent->left = nil;

+		if(p->parent->left == p)

+			p->parent->left = nil;

+		else{

+			for(q=p->parent->left; q->right!=p; q=q->right)

+				;

+			assert(q != nil);

+			q->right = p->right;

+		}

 		p->parent = nil;

 		*queue = mergequeue(p, *queue);

 	}

@@ -115,5 +126,6 @@

 	p->n = n;

 	p->aux = aux;

 	*queue = mergequeue(p, *queue);

+	dprint(Logtrace, "pheap::pushqueue %#p %.6f\n", p, p->n);

 	return p;

 }