_Follow along with this video:_ --- ### Exploits, but smaller ```js // Check for duplicates for (uint256 i = 0; i < players.length - 1; i++) { for (uint256 j = i + 1; j < players.length; j++) { require(players[i] != players[j], "PuppyRaffle: Duplicate player"); } } ``` This code above is going to cause something called a Denial of Service or DOS. In order to get a better understanding of this bug, let's look at a _minimized_ example of it. If you reference the [**sc-exploits-minimized**](https://github.com/Cyfrin/sc-exploits-minimized) repo, half way down you should see something like what's pictured below. ::image{src='/security-section-4/10-sc-exploits-minimized/sc-exploits-minimized1.png' style='width: 75%; height: auto;'} This is an amazing resource to test your skills in general and familiarize yourself with common exploits. Additionally, the `src` folder of `sc-exploits-minimized` contains minimalistic examples of a variety of vulnerabilities as well. For now, let's check out the [**Remix example**](https://remix.ethereum.org/#url=https://github.com/Cyfrin/sc-exploits-minimized/blob/main/src/denial-of-service/DoS.sol&lang=en&optimize=false&runs=200&evmVersion=null&version=soljson-v0.8.20+commit.a1b79de6.js) of the Denial of Service exploit in the next lesson.