There's quite an extended back and forth in actual interviews for questions like this, so nothing quite like real practice. The Prepfully Skyscanner Software Engineer experts have actually worked in this role, so they're able to do an honest-to-God accurate mock, which really puts you through the paces. prepfully.com/practice-interviews

Clearly didn't make it very far in the Big 4 application process if you think Skyscanner's interviews were as hard as them.