If a club tracks entries and exits using an array of 1's(entries) and 0's(exits) devise a "Divide and Conquer" algorithm that tells you if it's a valid array in O(n) time.

The array is valid if a)there is an equal number of entries and exits and b)if the number of exits never exceeds the number of entries when reading the array from left to right(for example, given [1,0,0,1,1,0] the # of exits temporarily exceed the # of entries)