Candidates can employ several strategies to memorize vast topics for UPSC, such as utilizing mnemonic devices, active recall techniques, and spaced repetition. Breaking down information into smaller, manageable chunks can enhance retention and understanding. Additionally, summarizing notes in one's own words promotes deeper engagement with the material. Visual aids like diagrams or flowcharts can also facilitate memory by connecting concepts visually. Regular self-quizzing on key topics reinforces learning, while teaching concepts to peers can further solidify understanding. Together, these strategies enhance memory retention during preparation.