Infinity NFT Marketplace contest - Tadashi's results

Operations in relational expression can be optimized

Details: By using De Morgan's laws is possible to prove that L77-79 of InfinityOrderBookComplication.sol is equivalent to:

if (!(isOrdersTimeValid && itemsIntersect)) {
	return false; // short circuit
}

The latter code saves gas since a NOT instruction is avoided. Alternatively, consider splitting the if in two to avoid usage of || (see Simplifying if-else statements can save gas below for more details).

Simplifying if-else statements can save gas

Details: The following changes produces equivalent code and avoid the usage of || operator:

• Changing L77-79 of InfinityOrderBookComplication.sol to

  if (!isOrdersTimeValid){ 
  	return false; 
  }
  if (!itemsIntersect) {
  	return false; 
  }

• Changing L240-242 of InfinityOrderBookComplication.sol to

  if (order1NftsLength == 0){ 
  	return true;
  }
  if (order2NftsLength == 0){ 
  	return true;
  }

• Changing L286-288 of InfinityOrderBookComplication.sol to

  if (item1TokensLength == 0){
  	return true;
  }
  if (item2TokensLength == 0){
  	return true;
  }

• Changing L334-336 of InfinityOrderBookComplication.sol to

  if (priceDiff == 0) {
  	return startPrice;
  }
  if (duration == 0) {
  	return startPrice;
  }

Unnecessary require can be removed

Details: The require on L193 of InfinityStaker.sol can be removed since the variable totalStaked is of type uint256.

Note: Another alternative is to replace the code of L193 to

require(totalStaked > 0, 'nothing staked to rage quit');

which seems to be the original intent of the code authors.

Remove unnecessary fallback functions

Details: The fallback function in L119 of InfinityExchange.sol can be removed, as it does not have any logic implemented inside it and the InfinityExchange contract already has a receive function in L121. The same applies to the fallback function in L55 of InfinityStaker.sol