[LeetCode]Min Stack

题目描述:(链接)

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.

解题思路:

class MinStack {
public:
    void push(int x) {
        elems.push(x);
        if (minElems.empty() || minElems.top() >= x) {
            minElems.push(x);
        }
    }

    void pop() {
        if (elems.top() == minElems.top()) {
            minElems.pop();
        }
        elems.pop();
    }

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

    int getMin() {
        return minElems.top();
    }
private:
    stack<int> elems;
    stack<int> minElems;
};