id summary reporter owner description type status priority milestone component version resolution keywords cc revision 627 O(1) time to get an arc from node u and node v zhaofeng-shu33 Alpar Juttner "is there any graph structure in lemon library which supports getting an arc from its two nodes in O(1) times? I check ListDigraph, by iterating all arcs connected with one node, I can achieve this purpose but it could be O(n)." enhancement closed major LEMON 1.4 release core hg main invalid