leet-code/src/main/java/leetcode/editor/cn/YongLiangGeZhanShiXianDuiLieLcof.java

//用两个栈实现一个队列。队列的声明如下，请实现它的两个函数 appendTail 和 deleteHead ，分别完成在队列尾部插入整数和在队列头部删除整数的
//功能。(若队列中没有元素，deleteHead 操作返回 -1 ) 
//
// 
//
// 示例 1： 
//
// 输入：
//["CQueue","appendTail","deleteHead","deleteHead"]
//[[],[3],[],[]]
//输出：[null,null,3,-1]
// 
//
// 示例 2： 
//
// 输入：
//["CQueue","deleteHead","appendTail","appendTail","deleteHead","deleteHead"]
//[[],[],[5],[2],[],[]]
//输出：[null,-1,null,null,5,2]
// 
//
// 提示： 
//
// 
// 1 <= values <= 10000 
// 最多会对 appendTail、deleteHead 进行 10000 次调用 
// 
// Related Topics 栈 设计 
// 👍 212 👎 0

package leetcode.editor.cn;

import java.util.Stack;

//剑指 Offer 09:用两个栈实现队列
public class YongLiangGeZhanShiXianDuiLieLcof {
    public static void main(String[] args) {
        //测试代码
//        Solution solution = new YongLiangGeZhanShiXianDuiLieLcof().new Solution();
    }

    //力扣代码
    //leetcode submit region begin(Prohibit modification and deletion)
    class CQueue {
        Stack<Integer> stack1;
        Stack<Integer> stack2;

        public CQueue() {
            stack1 = new Stack<>();
            stack2 = new Stack<>();
        }

        public void appendTail(int value) {
            stack1.push(value);
        }

        public int deleteHead() {
            if (stack2.isEmpty()) {
                while (!stack1.isEmpty()) {
                    stack2.push(stack1.pop());
                }
            }
            return stack2.isEmpty() ? -1 : stack2.pop();
        }
    }

/**
 * Your CQueue object will be instantiated and called as such:
 * CQueue obj = new CQueue();
 * obj.appendTail(value);
 * int param_2 = obj.deleteHead();
 */
//leetcode submit region end(Prohibit modification and deletion)

}