Please note that not every Warcraft 3 custom map is saving a hash value to a file on your machine. That means its also a good idea to take a screenshot or a photo of your savecode if you play custom maps which allows you to save your progress.
This is the main location where you will find .txt files which holding your custom map save game data / code.
This is the main location for Mac where you can find the custom map save game data / code.
~/Library/Application Support/Blizzard/Warcraft III/CustomMapData/