LeetCode 155 Min Stack - Implementation

Each entry stores (value, min_at_this_point).

class MinStack: def init(self): self.stack = []

def push(self, val):
    if not self.stack:
        self.stack.append((val, val))
    else:
        curr_min = min(val, self.stack[-1][1])
        self.stack.append((val, curr_min))

def pop(self):
    self.stack.pop()

def top(self):
    return self.stack[-1][0]

def getMin(self):
    return self.stack[-1][1]

All operations $O(1)$ time, $O(n)$ space total.