[刷题]Min Stack

public class Solution {
Stack<Integer> stack;
Stack<Integer> minStack;

public Solution() {
// 2015-09-04
stack = new Stack<>();
minStack = new Stack<>();
}

public void push(int number) {
stack.push(number);
if (!minStack.isEmpty() && minStack.peek() < number) {
minStack.push(minStack.peek());
} else {
minStack.push(number);
}
}

public int pop() {
minStack.pop();
return stack.pop();
}

public int min() {
return minStack.peek();
}
}