Algorithm 1. IACO algorithm

Set parameters: $ant$ (number of all ants), $ant$ (number of iteration), $\alpha$, $\beta$, $\rho$, $Q$ Input: $T$, $U$ Output: best tasks path list $G$ Initialize heuristic information and pheromone matrices. 1. for $i=1:iter$ do 2.  for $j=1:ant$ do 3.   for $u=1:m$ do 4.    Calculate the utility between users and tasks; 5.    Calculate selection probability; 6.    if $i=1$ 7.     Select next task with the greatest utility 8.    else 9.     Select next task by roulette; 10.    end if 11.    Add the selected task into taboo list; 12.    Leave the pheromone 13.   end for 14.  end for 15. end for 16. return taboo list