Challenge: Multiple Values

Given an array, answer queries: what are the $k$ smallest values in range $[l, r]$? Sparse table for min gives only the smallest. For top-$k$, you need more storage.

Approach: at each $\text{st}[i][j]$, store the $k$ smallest values in that range. Merge by combining two sorted lists and keeping the smallest $k$. Space: $O(nk \log n)$.

Build: $O(nk \log n)$. Query: $O(k)$. This works when $k$ is small and fixed. For variable $k$, consider other structures like wavelet trees.