leetCode(45):Min Stack 分类： leetCode 2015-07-20 08:34 139人阅读 评论(0) 收藏

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) {
data.push(x);//数据栈正常压入
if(minData.empty())
{//最小栈数据栈压入时要进行判断，如果被压入的数据不影响最小值，则直接再压入

//最小栈栈顶元素，否则压入x
minData.push(x);
}
else
{
if(x<minData.top())
{
minData.push(x);
}
else
{
minData.push(minData.top());
}
}
}

void pop() {//弹出时，两个栈都需要弹出
data.pop();
minData.pop();
}

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

int getMin() {
return minData.top();
}

private:
stack<int> data;
stack<int> minData;
};