import java.util.Stack;
class MinStack {
//没有必要把所有元素都记录下来
Stack<Integer> stack = new Stack<>();
Stack<Integer> minStack = new Stack<>();
/** initialize your data structure here. */
public MinStack() {
}
public void push(int x) {
stack.push(x);
if(!minStack.isEmpty()){
if(x <= minStack.peek())
minStack.push(x);
}
else{
minStack.push(x);
}
}
public void pop() {
if(!stack.isEmpty()){
int temp = stack.pop();
if(!minStack.isEmpty()){
if(temp == minStack.peek()){
minStack.pop();
}
}
}
}
public int top() {
return stack.peek();
}
public int getMin() {
return minStack.peek();
}
}
/**
* 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();
*/