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dfs序七个经典问题 参考自：《数据结构漫谈》 许昊然 dfs序是树在dfs先序遍历时的序列，将树形结构转化成序列问题处理。 dfs有一个很好的性质：一棵子树所在的位置处于一个连续区间中。 ps:deep[x]为x的深度，l[x]为dfs序中x的位置，r[x]为dfs序中x子树的结束位置 1.点修改 阅读全文
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You are given an array d1,d2,…,dn consisting of n integer numbers. Your task is to split this array into three parts (some of which may be empty) in s 阅读全文
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1.POJ上G++只能用 %f，C++可以%lf 2.连续区间异或和最大，我只会一个套路，就是01字典树了！ 3.行和列是无关的，因此有时候可以把棋盘原题分解成两个一维问题。r[N]、c[N]... 4.线段树：当前区间加上了懒惰标记的值实际上加的值是lazy_tag 区间长度 5.线段树：成段更新 阅读全文
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Polycarp is practicing his problem solving skill. He has a list of n problems with difficulties a1,a2,…,an, respectively. His plan is to practice for 阅读全文
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Polycarp has n coins, the value of the i th coin is ai. It is guaranteed that all the values are integer powers of 2 (i.e. ai=2d for some non negative 阅读全文