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.

class MinStack {
public:
    void push(int x) 
    {
        int n = min.size();
        data.push(x);
        if(n==0)
        {
            min.push_back(x);
            count.push_back(1);
        }
        else
        {
            int t = min[n-1];
            if(t>x)
            {
                min.push_back(x);
                count.push_back(1);
            }
            else
            {
                count[n-1]++;
            }
        }
    }

    void pop() 
    {
        int n = min.size()-1;
        data.pop();
        if(count[n]>1)
            count[n]--;
        else
        {
            min.pop_back();
            count.pop_back();
        }
    }

    int top() 
    {
        return data.top();
    }

    int getMin() 
    {
        int n = min.size()-1;
        return min[n];
    }
private:
    stack<int> data;
    vector<int> min;
    vector<int> count;
};

LeetCode--Min Stack