my @item_array = {{1, 2, 20}, {2, 3, 15}, {3,4,3}, {4, 5, 17}, {5,6,28}, {6,1,23}, {1, 7, 1}, {2, 7, 4}, {3, 7, 9,}, {4, 7, 16}, {5, 7, 25}, {6, 7, 36}};