Should save current minimum value in stack for O(1) time complexity.
class MinStack:
def __init__(self):
"""
initialize your data structure here.
"""
self.stack = []
def push(self, x: int) -> None:
if len(self.stack) == 0:
self.stack.append({'value': x, 'min': x})
else:
self.stack.append({'value': x, 'min': min(x, self.stack[-1]['min'])})
def pop(self) -> None:
del self.stack[-1]
def top(self) -> int:
return self.stack[-1]['value']
def getMin(self) -> int:
return self.stack[-1]['min']
# Your MinStack object will be instantiated and called as such:
# obj = MinStack()
# obj.push(x)
# obj.pop()
# param_3 = obj.top()
# param_4 = obj.getMin()
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