How is the problem solved in the book Ender's Game?

Answer 1

By Ender destroying all the aliens on their homeworld and every where else. He thought it was a game.

The ultimate problem -- Ender's guilt in destroying the alien race -- was resolved at the end of the novel and in its sequel, Speaker for the Dead. In order for Ender to really know his enemies well enough to defeat them, he inevitably had to come to love them. For this reason, he understands the buggers' intentions better than anyone else on Earth and is left with immense guilt in for destroying them (despite the fact that he didn't realize it was real). He becomes the anonymous Speaker for the Dead and reveals the true nature of the buggers to humanity (ironically damning himself as "Ender the Xenocide" in the eyes of the human race), and he's given a chance to rebuild the alien race he thought he had wiped out entirely when he finds a last hive queen egg.

Answer 2

In the book "Ender's Game," the problem of the alien threat is solved by using Ender Wiggin's tactical brilliance in leading the human fleets to victory against the Formic aliens. Ender's unique understanding of the enemy's strategies and motivations allows him to outmaneuver the aliens and ultimately put an end to the threat they pose.