However, I believe that if the problem of corruption can be addressed at a young age, every country's degree of corruption will significantly decline in the near future.
The surest way to discourage corruption is to state clearly strong punishments for defaulters and ensure that the defaulters are made to face the full penalty of the law. If an example is made out of some individuals, it can prompt change which can have a ripple effect on the mindset of other individuals. Corruption can be an effect of an environmental factor that is when everyone around you is corrupt it is difficult for you to maintain an incorruptible culture, In other words, an environment full of incorruptible people can turn a corrupt person for the better.
Corruption is rooted on many countries nowadays. It's not seen as something people should fight at all costs anymore, but something that people should learn how to live with. I agree when you say about punishing defaulters with the maximum rigor of the law, however the most important factor to decrease corruption levels is when you live in a society based on loyalty and honor. A society which has strong principles followed by its leaders and older generations will forge new generations on the right path as well.