Algorithm 2 CO-CFG Algorithm

1:Initialize: The set of UAVs is $\left\{1,2,3,\cdots ,N\right\}$, initial coalition structure is ${\Pi }^0=\left\{\left\{1\right\},\left\{2\right\},\cdots ,\left\{N\right\}\right\}$ and the historical selection set is ${\left\{H_n\right\}}_{n\in N}=⌀$. 2:repeat 3:   Step 1: Calculate the utility $u_n$ of UAV n, the utility $U_{S_k}$ of coalition and the total system utility under the current coalition structure. 4:   Step 2: UAV n selects a coalition from the existing coalitions, and calculates its own utility, coalition utility and system utility after joining. Judging whether UAV n meets the following transfer conditions after it transfers from the current coalition $S_j$ to the new coalition $S_i$: 5:      (a) The utility of UAV n is increasing, i.e., $u_n\left(S_i\right)>u_n\left(S_j\right)$; 6:      (b) The system utility is increasing as defined in cooperation order; 7:      (c) The new coalition $S_i$ does not exist in the historical selection set. 8:       If the transfer conditions are met, the coalition $S_i$ is added to the candidate set ${Ca}_n$. Otherwise, a new coalition is selected to join. 9:   Step 3: If $C{a}_n\ne ⌀$, UAV n joins the optimal coalition $S_{opt}$ which maximizes system utility, and $S_{opt}$ is added to $H_n$. 10:   Step 4: Update coalition structure $\Pi$. Otherwise, the historical selection set will not be changed. 11:until the historical selection set no longer changes.