We can do this by adding a boolean dirty flag to each node. If it’s set to true, then this is a node that needs to be recalculated. Otherwise, it’s up-to-date. Let’s start with these flags all set to false — we have an up-to-date tree. Now, when we update the input node, we can iterate over all the children of that node, and follow a simple algorithm:
Gas also dropped, with UK prices for month-ahead delivery falling sharply to 119p a therm, well below Monday's peak of 171p.，推荐阅读新收录的资料获取更多信息
13年不懈奋斗、近1亿人稳定脱贫，中国为什么能？。新收录的资料对此有专业解读
04:06, 11 марта 2026Ценности
println(42); // prints "42\n"