Leetcode 946. Validate Stack Sequences
class Solution:
def validateStackSequences(self, pushed: List[int], popped: List[int]) -> bool:
stack = []
while len(popped) > 0:
e = popped[0]
while (not stack or e != stack[-1]) and len(pushed) > 0:
stack.append(pushed.pop(0))
if e != stack[-1]:
return False
popped.pop(0)
stack and stack.pop()
return len(pushed) == 0 and len(popped) == 0