Remove from Prufer set and print pair .
vertex_set [ j ] = - 1 NEW_LINE print ( " ( " , ( j + 1 ) , " , ▁ " , prufer [ i ] , " ) ▁ " , sep = " " , end = " " ) NEW_LINE vertex_set [ prufer [ i ] - 1 ] -= 1 NEW_LINE break NEW_LINE j = 0 NEW_LINE