LeetCode Min Stack

LeetCode Min Stack

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

• Push (x) -- Push element x onto stack.
• Pop () -- Removes the element on top of the stack.
• Top () -- Get the top element.
• GetMin () -- Retrieve the minimum element in the stack.
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  Question: write a new stack: Support for inbound and outbound stacks, get the top of the stack, and get the minimum number of stacks at this time.

  Idea: the first three operations can be implemented using one stack. To minimize the number of operations, a new monotonous stack is required for maintenance. Note the following points for the new monotonous Stack: when the original stack pop drops a number, it may affect this monotonous stack. If the pop drops at this time, it can be solved if it is the top of the monotonous stack, because this monotonous stack is a subset of the original Stack

  
  

  class MinStack {public:    void push(int x) {        st.push(x);        if (stm.empty() || stm.top() >= x) stm.push(x);    }    void pop() {        int top = st.top();        st.pop();        if (top == stm.top()) stm.pop();    }    int top() {        return st.top();    }    int getMin() {        return stm.top();    }    private:        stack
     
       st;        stack
      
        stm;};