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[NOIP2001 Popularization Group] Seek Ranking

Question analysis: The question mentions the pre-order, in-order, and post-order arrangement of trees, so we need to know what these three arrangements mean first. 3 (depth-first) permutations of binary trees: Pre-order, "root left and right". That is, for each subtree of the binary tree, first visit its root, and then traverse its left and right […]