https://leetcode.com/problems/validate-stack-sequences/
func validateStackSequences(_ pushed: [Int], _ popped: [Int]) -> Bool {
var result: [Int] = []
var mypoped = popped
for item in pushed {
result.append(item)
while !result.isEmpty && result.last == mypoped.first {
result.removeLast()
mypoped.removeFirst()
}
}
return result.count == 0 ? true : false
}