摘要：
https://leetcode.com/problems/robot-return-to-origin/ There is a robot starting at position (0, 0), the origin, on a 2D plane. Given a sequence of its 阅读全文
摘要：
https://pintia.cn/problem-sets/994805342720868352/problems/994805359372255232 Given a tree, you are supposed to tell if it is a complete binary tree. 阅读全文
摘要：
https://pintia.cn/problem-sets/994805342720868352/problems/994805388447170560 A supply chain is a network of retailers（零售商）, distributors（经销商）, and su 阅读全文
摘要：
https://pintia.cn/problem-sets/994805342720868352/problems/994805355987451904 A Binary Search Tree (BST) is recursively defined as a binary tree which 阅读全文
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https://pintia.cn/problem-sets/994805342720868352/problems/994805372601090048 A family hierarchy is usually presented by a pedigree tree where all the 阅读全文