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(x)
—— 将元素 x 推入栈中。pop()
—— 删除栈顶的元素。top()
—— 获取栈顶元素。getMin()
—— 检索栈中的最小元素。
示例:
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:
pop
、top
和getMin
操作总是在 非空栈 上调用。
C#代码
public class MinStack {
private Stack<Tuple<int, int>> stack;
/** initialize your data structure here. */
public MinStack() {
stack = new Stack<Tuple<int, int>>();
}
public void Push(int x) {
var min=x;
if(stack.Any()){
var top = stack.Peek();
min = Math.Min(top.Item2,min);
}
stack.Push(Tuple.Create(x,min));
}
public void Pop() {
stack.Pop();
}
public int Top() {
var top = stack.Peek();
return top.Item1;
}
public int GetMin() {
var top = stack.Peek();
return top.Item2;
}
}
/**
* Your MinStack object will be instantiated and called as such:
* MinStack obj = new MinStack();
* obj.Push(x);
* obj.Pop();
* int param_3 = obj.Top();
* int param_4 = obj.GetMin();
*/