Block　copolymer　directed　self-assembly　(DSA)　is　a　simple　and　promising　candidate　next-generation　device　fabrication　technology,　which　is　low-cost　as　complement　with　multi-patterning　for　contact　layer　patterning.　In　this　paper,　we　consider　the　contact　layer　mask　and　template　assignment　problem　of　DSA　with　triple　patterning　lithography　of　general　layout.　To　address　this　problem,　first　we　construct　a　weighted　conflict　grouping　graph,　in　which　edges　with　negative　weights　are　introduced,　then　a　discrete　relaxation　based　mask　assignment　problem　is　proposed.　The　integer　linear　program　(ILP)　formulation　of　the　discrete　relaxation　problem　is　solved　for　obtaining　a　lower　bound　on　the　optimal　value　of　this　problem.　In　order　to　improve　the　lower　bound,　some　valid　inequalities　are　introduced　to　prune　some　poor　relaxation　solutions.　At　last,　the　obtained　discrete　relaxation　solution　is　transformed　to　a　legal　solution　of　the　original　problem　by　solving　a　template　assignment　problem　on　the　layout　graph,　which　provides　an　upper　bound　on　the　optimal　value　of　the　original　problem.　Experimental　results　and　comparisons　show　the　effectiveness　and　efficiency　of　our　method.　In　addition,　under　the　discrete　relaxation　theory,　the　quality　of　our　experimental　results　can　be　evaluated　by　the　obtained　upper　and　lower　bounds.　Specifically,　the　gap　between　the　obtained　upper　and　lower　bounds　is　0　for　most　of　the　sparse　benchmarks,　and　the　average　gap　is　0.4%　for　dense　benchmarks.