Operation : Change any array element to arbitrary integer, O(N^2) would give TLE, My approach : ans = Length of array — Length of longest non-decreasing sub-sequence because I want maximum length already sorted, TC : O(NlgN),
Is this approach correct? Any other approaches?
I think you're right. Since changing an element can be seen as simply delete it, the problem is actually finding a longest sorted subsequence. Thus it's indeed a LIS problem.
This problem is from a hiring challenge.