题目描述:()

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:

1 class MinStack { 2 public: 3     void push(int x) { 4         elems.push(x); 5         if (minElems.empty() || minElems.top() >= x) { 6             minElems.push(x); 7         } 8     } 9 10     void pop() {11         if (elems.top() == minElems.top()) {12             minElems.pop();13         }14         elems.pop();15     }16 17     int top() {18         return elems.top();19     }20 21     int getMin() {22         return minElems.top();23     }24 private:25     stack
     
       elems;26     stack
      
        minElems;27 };