Interview Questions

BFS explores level by level using a queue — best for shortest path in unweighted graphs. DFS goes as deep as possible using a stack/recursion — useful for topological sort, cycle detection, and exploring all paths. Both are O(V+E).

DP solves problems by breaking them into overlapping subproblems and storing results (memoization or tabulation) to avoid recomputation. Use it when a problem has optimal substructure and overlapping subproblems — e.g. knapsack, edit distance, longest common subsequence.