Create Maximum - Max from One Array

To get the maximum number of length $m$ from an array of length $n$:

Use a monotonic decreasing stack. For each digit, while the stack is not empty, the top is smaller, and you have enough remaining digits to fill $m$ slots, pop the stack.

Push the current digit if the stack size is less than $m$.

function maxFromOne(nums, m)
 stack := []
 drop := length - m
 for d in nums
 while stack not empty and stack.top < d and drop > 0
 stack.pop()
 drop := drop - 1
 if stack.size < m then
 stack.push(d)
 return stack