Definitions
- Subsequence (length k): pick any
kelements fromvaluesby choosing indicesi1 < i2 < ... < ik(not necessarily contiguous). - Median: sort the chosen
kelements intob. The median isb[(k-1)/2](0-based, integer division), i.e., the lower median whenkis even.
Task
- Enumerate all subsequences of length
k. - For each subsequence, sort it and compute its median (as defined above).
- Return
[maxMedian, minMedian]across all length-ksubsequences.
Example 1
values = [1, 2, 3]
k = 2
All length-2 subsequences (order chosen by indices):
[1, 2]→ sorted[1, 2]→ median =1[1, 3]→ sorted[1, 3]→ median =1[2, 3]→ sorted[2, 3]→ median =2
Output: [2, 1]
Example 2
values = [5, 1, 4, 2]
k = 3
All length-3 subsequences (4 choose 3 = 4):
[5, 1, 4]→ sorted[1, 4, 5]→ median =4[5, 1, 2]→ sorted[1, 2, 5]→ median =2[5, 4, 2]→ sorted[2, 4, 5]→ median =4[1, 4, 2]→ sorted[1, 2, 4]→ median =2
Output: [4, 2]
Constraints
1 ≤ n ≤ 1e50 ≤ values[i] ≤ 1e91 ≤ k ≤ n