Keep track the history of the keyword to determine when a keyword is rising or down in popularity over time.
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，这一点在Line官方版本下载中也有详细论述
Every Tuesday, Guardian rugby writer Robert Kitson gives his thoughts on the headlines, scrutinises the latest matches and provides gossip from behind the scenes in his unique and indomitable style. See the latest edition here.，推荐阅读旺商聊官方下载获取更多信息
* 1. 转换视角：将"追车"问题转为"到达时间"比较（后车时间≤前车 → 合并）；