Given two integer arrays pushed and popped each with distinct values, return true__ if this could have been the result of a sequence of push and pop operations on an initially empty stack, or __false__ otherwise.__
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.
1 <= pushed.length <= 1000 0 <= pushed[i] <= 1000 All the elements of pushed are unique. popped.length == pushed.length popped is a permutation of pushed.
class Solution: def validateStackSequences(self, pushed: List[int], popped: List[int]) -> bool: stack =  i = 0 for v in pushed: stack.append(v) # check if we need to pop popped(move index instead) while stack and i < len(popped) and popped[i] == stack[-1]: stack.pop() i += 1 return i == len(popped) # not stack