PaulRBerg

Gas Fee Models on EVM Chains

Chain	Type	Min Tx Gas	Model	Explanation
Arbitrum	Optimistic Rollup	35-70k	Multifunctional gas limit	Bake L1 data fee into L2 gas limit
BNB Chain	Sidechain	21k	EVM	Same as vanilla EVM
Gnosis	Sidechain	21k	EVM	Same as vanilla EVM
OP Stack	Optimistic Rollup	21k	Two-dimensional fees	Explicit L2 execution fee and implicit L1 DA fee
Polygon	Sidechain	21k	EVM	Same as vanilla EVM

cwhinfrey

ChainSwap 1

• $800k
• July 2, 2021
• Vulnerability: Smart contract bug
• Note: Users reported lost funds, ChainSwap shut down all nodes and a fix was deployed within 30 minutes.
• Source: https://chain-swap.medium.com/chainswap-post-mortem-and-compensation-plan-90cad50898ab

ChainSwap 2

• $4.4M
• July 10, 2021
• Vulnerability: Smart contract bug

0xkarmacoma

Sending Ether Cheat Sheet

TLDR

🥇 Instead of sending Ether, use the withdrawal pattern

🥈 If you really need to send Ether, use a safe wrapper like OpenZeppelin's Address.sendValue(addr, amount)

🥉 If you really need to send Ether without dependencies, use (bool success, ) = addr.call{value: amount}("")

subhodi

pragma solidity ^0.4.18;

contract QuickSort {
    
    function sort(uint[] data) public constant returns(uint[]) {
       quickSort(data, int(0), int(data.length - 1));
       return data;
    }
    
    function quickSort(uint[] memory arr, int left, int right) internal{