ICOPool is a smart contract for pooling together contributions to invest in an ICO.

Once deployed, the ICOPool contract can be in one of four states: Open, Failed, Refund, or Paid

In the Open state contributors are able to deposit funds to the pool or withdraw funds from their contributions.

In the Failed or Refund state contributors can only withdraw their funds from the pool.

In the Paid state contributors can withdraw funds which were not included in the pool's overall contribution to the ICO. After the contract creator sets token contract on ICOPool, contributors will able to obtain their tokens. There is also a method for delivering the tokens to all the pool's contributors which can be invoked by the the contract creator.

The operation to transition to a Paid state is O(1). Similarly, the contributor operations (deposit eth, withdraw eth, obtain tokens) are O(1). The operation to deliver tokens to all the pool's contributors is O(n) where n is the number of contributors. This operation is likely to fail for pools consisting of many contributors because of gas limits.

In some cases editing the contribution limits can be an O(n) operation. Adding or removing a whitelist is an O(n) operation. Modifying an existing whitelist is an O(w) operation where w is the sum of additions and deletions on the whitelist.