Programming & Data Structures for GATE

This is the heaviest core subject and the one where careful, mechanical work pays most. C questions are output-prediction problems, and the only reliable method is to draw the memory rather than reason about the code in your head, because C is a thin layer over addresses and every trick question exploits that. Recursion questions are answered by writing the call tree, not by tracing mentally. For data structures, the organising question is always where insertions and deletions are allowed, which is what distinguishes a stack from a queue from a deque. Tree questions come down to counting arguments or traversals, and heap and graph questions come down to maintaining only what the queries actually need. Attempt the pointer-heavy questions when you are fresh.