Well, it may not have charged the laptop at all, due to the cord being in water. I would try another cord and see if it charges.
If it doesn't, then the laptops charging circuit, the motherboard and/or the battery could have been fried when the charger cord got in the water. For those you would have to open up the laptop to check.
Now if the laptop is under warranty, you may want to call the manufacturer about the issue and see if it would be covered. If it isn't under warranty, then you can do the testing and work yourself, or get a tech to do it.