数组·prototype·last·core·interview·pattern 模式

识别信号

• Do you handle empty arrays explicitly to avoid undefined?
• Are you modifying Array.prototype directly or using a helper function?

解题流程

1. 1. 明确窗口/状态定义
2. 2. 更新状态并维护约束
3. 3. 用边界样例验证

常见失分点

• Accessing this[this.length] instead of this[this.length-1] causing undefined.