cpp-flashcards/org/study_deck_02/dsa/stack/0155-min-stack.org

• 0155. Min Stack
  • Approach
  • Python
  • C++

TODO 0155. Min Stack   medium

Design a stack that supports push, pop, top, and retrieving the minimum element in constant time.

Implement the MinStack class:

• MinStack() initializes the stack object.
• void push(int val) pushes the element val onto the stack.
• void pop() removes the element on the top of the stack.
• int top() gets the top element of the stack.
• int getMin() retrieves the minimum element in the stack.

You must implement a solution with O(1) time complexity for each function.

Example 1:

Input
["MinStack","push","push","push","getMin","pop","top","getMin"]
[[],[-2],[0],[-3],[],[],[],[]]

Output
[null,null,null,null,-3,null,0,-2]

Explanation
MinStack minStack = new MinStack();
minStack.push(-2);
minStack.push(0);
minStack.push(-3);
minStack.getMin(); // return -3
minStack.pop();
minStack.top();    // return 0
minStack.getMin(); // return -2

Constraints:

• -2^{31} <= val <= 2^{31} - 1
• Methods pop, top and getMin operations will always be called on non-empty stacks.
• At most 3 * 10^{4} calls will be made to push, pop, top, and getMin.

TODO Approach

Write your approach here.

TODO Python

class MinStack:

    def __init__(self):
        

    def push(self, val: int) -> None:
        

    def pop(self) -> None:
        

    def top(self) -> int:
        

    def getMin(self) -> int:
        


# Your MinStack object will be instantiated and called as such:
# obj = MinStack()
# obj.push(val)
# obj.pop()
# param_3 = obj.top()
# param_4 = obj.getMin()

TODO C++

class MinStack {
public:
    MinStack() {
        
    }
    
    void push(int val) {
        
    }
    
    void pop() {
        
    }
    
    int top() {
        
    }
    
    int getMin() {
        
    }
};

/**
 * Your MinStack object will be instantiated and called as such:
 * MinStack* obj = new MinStack();
 * obj->push(val);
 * obj->pop();
 * int param_3 = obj->top();
 * int param_4 = obj->getMin();
 */