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Given a binary tree, determine if it is a valid binary search tree (BST). Assume a BST is defined as follows: The left subtree of a node contains only 阅读全文
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Description Write an algorithm to determine if a number n is "happy". A happy number is a number defined by the following process: Starting with any p 阅读全文
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第 175 场周赛 Description Implement the class TweetCounts that supports two methods: 1. recordTweet(string tweetName, int time) Stores the tweetName at th 阅读全文
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Description Building and maintaining roads among communities in the far North is an expensive business. With this in mind, the roads are build such th 阅读全文
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Description Polygon is a game for one player that starts on a polygon with N vertices, like the one in Figure 1, where N=4. Each vertex is labelled wi 阅读全文