设计一个支持 push ,pop ,top 操作,并能在常数时间内检索到最小元素的栈。
push
pop
top
实现 MinStack 类:
MinStack
MinStack()
void push(int val)
void pop()
int top()
int getMin()
示例 1:
输入: ["MinStack","push","push","push","getMin","pop","top","getMin"] [[],[-2],[0],[-3],[],[],[],[]] 输出: [null,null,null,null,-3,null,0,-2] 解释: MinStack minStack = new MinStack(); minStack.push(-2); minStack.push(0); minStack.push(-3); minStack.getMin(); --> 返回 -3. minStack.pop(); minStack.top(); --> 返回 0. minStack.getMin(); --> 返回 -2.
提示:
-231 <= val <= 231 - 1
getMin
3 * 104