Given two sequences pushed and popped with distinct values, return true if and only if this could have been the result of a sequence of push and pop operations on an initially empty stack.
Example 1:
Input: pushed = [1,2,3,4,5], popped = [4,5,3,2,1]
Output: true
Explanation: We might do the following sequence:
push(1), push(2), push(3), push(4), pop() -> 4,
push(5), pop() -> 5, pop() -> 3, pop() -> 2, pop() -> 1
Example 2:
Input: pushed = [1,2,3,4,5], popped = [4,3,5,1,2]
Output: false
Explanation: 1 cannot be popped before 2.
Constraints:
0 <= pushed.length == popped.length <= 1000
0 <= pushed[i], popped[i] < 1000
pushed is a permutation of popped.
pushed and popped have distinct values.
class Solution:
    def validateStackSequences(self, pushed: List[int], popped: List[int]) -> bool:
        pushed.reverse()
        popped.reverse()
        
        stack = []
        while pushed:
            value = pushed.pop()
            stack.append(value)
            while stack and popped and stack[-1] == popped[-1]:
                popped.pop()
                stack.pop()
                
        if not pushed and not popped:
            return True
        return False
                

class Solution:
    def validateStackSequences(self, pushed: List[int], popped: List[int]) -> bool:
        pushed.reverse()
        popped.reverse()
        
        stack = []
        while pushed:
            value = pushed.pop()
            stack.append(value)
            while stack and popped and stack[-1] == popped[-1]:
                popped.pop()
                stack.pop()
                
        if not pushed and not popped:
            return True
        return False
                
