#552 · #857 · Minimum Cost to Hire K Workers(雇佣 K 名工人的最低成本)

There are n workers with quality[i] and a minimum expected wage wage[i]. Hire exactly k workers and pay each the same amount per unit of quality, at least their expectation. Return the minimum total cost. Constraints: 1 <= k <= n <= 10^4, 1 <= quality[i] <= 10^4, 1 <= wage[i] <= 10^4.