---
栈相关
---

#### [09. 用两个栈实现队列](https://leetcode-cn.com/problems/yong-liang-ge-zhan-shi-xian-dui-lie-lcof/)

```java
class CQueue {

    Stack<Integer> putStack, takeStack;

    public CQueue() {
        putStack = new Stack<>();
        takeStack = new Stack<>();
    }

    public void appendTail(int value) {
        putStack.push(value);
    }

    public int deleteHead() {
        if (takeStack.isEmpty()) {
            while (!putStack.isEmpty()) {
                takeStack.push(putStack.pop());
            }
        }
        if (takeStack.isEmpty()) {
            return -1;
        } else {
            return takeStack.pop();
        }
    }
}
```