Stack ? Cannot
Substring Problem Pattern ? Not
Then what type of Problem is it?
Treat 0 as -1 and 1 as +1. Then the whole binary sequence can be transferred into a height mountain digram. The solution is the same as finding the maximum distance between two same height.
This can be Done in O(n^2).
But unfortunately, it will cause TLE.
To get rid of the TLE, can we use DP?
This is a (2n+1) x 1 one dimensional DP.
The DP states are the two occurance of the current height.
The possible Heights are in the range of [-n, +n], total 2n + 1 cases.
So we can use a map to record the appearance of each height.