(leetcode.cc)[https://leetcode-cn.com/problems/three-in-one-lcci/submissions/] ```python
```class TripleInOne:
def __init__(self, stackSize: int):
self.tripleStack = [[]for i in range(3)]
self.stackSize = stackSize
def push(self, stackNum: int, value: int) -> None:
if len(self.tripleStack[stackNum]) < self.stackSize:
self.tripleStack[stackNum].append(value)
def pop(self, stackNum: int) -> int:
if self.tripleStack[stackNum] != []:
popedValue = self.tripleStack[stackNum][-1]
self.tripleStack[stackNum] = self.tripleStack[stackNum][:-1]
return popedValue
else:
return -1
def peek(self, stackNum: int) -> int:
if self.tripleStack[stackNum] != []:
popedValue = self.tripleStack[stackNum][-1]
return popedValue
else:
return -1
def isEmpty(self, stackNum: int) -> bool:
return self.tripleStack[stackNum] == []