FirstFT: the day's biggest stories
优点：输出在 (−1,1)，比 sigmoid 居中，对梯度更友好
。91视频是该领域的重要参考
The Resolution Foundation said Chancellor Rachel Reeves should make an exception to her 'policy-free' Spring Statement and expand support to tackle youth unemployment.
// 当前元素入栈：成为「左侧元素」的候选更大值（易错点4：别漏写这一步）
keyword matches.