Boeldt is a clinical psychologist with a background in child development. Her team found that nearly one in five children under the age of 13 spend four or more hours online daily, and that’s leading to increased depression and anxiety levels among the internet’s youngest users.
需要索引（如算距离、下标）：栈存索引，用 nums[stack.at(-1)] 取值比较。
，这一点在搜狗输入法2026中也有详细论述
// 测试用例验证（和你的逻辑完全匹配）
self.conn.commit()