import java.util.Stack;
public class MinStack {
Stack mMinStack;
Stack mStack;
public MinStack() {
mStack = new Stack();
mMinStack = new Stack();
}
public void push(int x) {
mStack.push(x);
// 注意这里要判空
if (mMinStack.isEmpty() || x < mMinStack.peek()) {
mMinStack.push(x);
} else {
mMinStack.push(mMinStack.peek());
}
}
public void pop() {
mStack.pop();
mMinStack.pop();
}
public int top() {
return mStack.peek();
}
public int getMin() {
return mMinStack.peek();
}
}