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# \[946]\[中等]\[贪心]\[栈] 验证栈序列

## 题目描述

[946. 验证栈序列](https://leetcode-cn.com/problems/validate-stack-sequences/)

给定 pushed 和 popped 两个序列，每个序列中的 值都不重复，只有当它们可能是在最初空栈上进行的推入 push 和弹出 pop 操作序列的结果时，返回 true；否则，返回 false 。

示例 1：

```
输入：pushed = [1,2,3,4,5], popped = [4,5,3,2,1]
输出：true
解释：我们可以按以下顺序执行：
push(1), push(2), push(3), push(4), pop() -> 4,
push(5), pop() -> 5, pop() -> 3, pop() -> 2, pop() -> 1
```

示例 2：

```
输入：pushed = [1,2,3,4,5], popped = [4,3,5,1,2]
输出：false
解释：1 不能在 2 之前弹出。
```

提示：

* 0 <= pushed.length == popped.length <= 1000
* 0 <= pushed\[i], popped\[i] < 1000
* pushed 是 popped 的排列。

## 解题思路

[Leetcode官方题解: 验证栈序列](https://leetcode-cn.com/problems/validate-stack-sequences/solution/yan-zheng-zhan-xu-lie-by-leetcode/)

```python
class Solution:
    def validateStackSequences(self, pushed: List[int], popped: List[int]) -> bool:
        stack = []
        left, right = 0, 0
        while left < len(pushed):
            stack.append(pushed[left])
            left += 1
            while stack and stack[-1] == popped[right]:
                stack.pop()
                right += 1
        return True if not stack else False
```