The Challenge contract invokes the solution contract to airdrop random amounts of ETH, ERC-20 tokens and ERC-721 NFTs to random addresses. The objective is to develop a solution contract that can perform the airdrop using minimal gas.
My submitted score: 1319998
Best score post-CTF, using this trick: 1296955
Summary of optimizations:
| Gas | Improvement | Description |
|---|---|---|
| 1382995 | Naive implementation | |
| 1380939 | 2056 | Configure compiler optimization for high runs |
| 1346939 | 34000 | Use access-list |
| 1337186 | 9753 | Avoid extra ERC20.transfer |
| 1334819 | 2367 | Avoid for-loops |
| 1322084 | 12735 | Precompute all random values and bake into Solver |
| 1322036 | 48 | payable functions slightly cheaper |
| 1320009 | 2027 | Use fallback function instead of individual functions |
| *1319998 | 11 | if-condition order makes a tiny difference |
| 1296955 | 23043 | Trick from curta team to use selfdestruct to send ETH cheaply |
*My submitted score.
Gas improvements have been committed one by one to make it easy to follow the optimization process.
To run challenge environment:
cd challenge/project/
pkill -9 anvil
anvil --fork-url https://mainnet.infura.io/v3/******************************** --auto-impersonate
forge script --rpc-url http://127.0.0.1:8545 script/Deploy.s.sol:Deploy --broadcast --unlocked --sender $(cast az)To test solution:
cd ../../solution/
npm install
npm run solve-localFurther gas reductions could be made by writing the solution in a lower-level language like Huff or in EVM bytecode directly.
Enjoy :)