Robber vaults rate: You are given an array vaults of positive integers where vaults[i] is the amount in the i-th vault, and an integer h (hours). In each hour you may steal from only one vault, removing up to k units from that single vault; you cannot split the hourly effort across multiple vaults. Find the minimum integer rate k such that all vaults are emptied within h hours. Describe your algorithm and its time complexity.
Subset sum: Given a set of distinct positive integers and a target, determine whether some subset sums exactly to the target. Outline an algorithm, analyze its complexity, and explain how to recover one valid subset if it exists.