Implement Queue using Stacks LeetCode solution in Python

1
# Runtime: 53 ms (Top 33.00%) | Memory: 13.9 MB (Top 98.49%)
2
class MyStack:
3
    def __init__(self):
4
        self.stack = []
5

6
    def push(self, x):
7
        self.stack.append(x)
8

9
    def top(self):
10
        return self.stack[-1]
11

12
    def pop(self):
13
        return self.stack.pop()
14

15
    def size(self):
16
        return len(self.stack)
17

18
    def isEmpty(self):
19
        return len(self.stack) == 0
20

21

22
class MyQueue:
23

24
    def __init__(self):
25
        self.stack1 = MyStack()
26
        self.stack2 = MyStack()
27

28
    def push(self, x: int) -> None:
29
        self.stack1.push(x)
30

31
    def pop(self) -> int:
32
        while not self.stack1.isEmpty():
33
            self.stack2.push(self.stack1.pop())
34
        out = self.stack2.pop()
35
        while not self.stack2.isEmpty():
36
            self.stack1.push(self.stack2.pop())
37
        return out
38

39
    def peek(self) -> int:
40
        while not self.stack1.isEmpty():
41
            self.stack2.push(self.stack1.pop())
42
        out = self.stack2.top()
43
        while not self.stack2.isEmpty():
44
            self.stack1.push(self.stack2.pop())
45
        return out
46

47
    def empty(self) -> bool:
48
        return self.stack1.isEmpty()
49

50

51
# Your MyQueue object will be instantiated and called as such:
52
# obj = MyQueue()
53
# obj.push(x)
54
# param_2 = obj.pop()
55
# param_3 = obj.peek()
56
# param_4 = obj.empty()