BCG X tends to care about how you think as much as code quality, so I’d prep for a mix rather than pure Leetcode. Are you targeting junior or mid level? I’ve seen a common pattern for similar software engineering interviews be a live coding round on data structures and algorithms plus a conversational behavioral chat, sometimes with a light system design discussion. I usually practice stories with a simple situation action result format and keep answers around 90 seconds, then run a timed mock with Beyz coding assistant after pulling a few prompts from the IQB interview question bank. Talking through your approach as you code helps a ton fwiw.