leetcode[155]Min Stack

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 {
private:
stack<int> sta;
stack<int> minsta;
public:
void push(int x) {
sta.push(x);
if(minsta.empty()||(!minsta.empty()&&x<=minsta.top()))
minsta.push(x);
}

void pop() {
if(sta.empty())return;
if(sta.top()==minsta.top())minsta.pop();
sta.pop();
}

int top() {
if(sta.empty())return INT_MAX;
return sta.top();
}

int getMin() {
if(minsta.empty())return INT_MAX;
return minsta.top();
}
};