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摘要： Given a binary tree, return the vertical order traversal of its nodes values. For each node at position (X, Y), its left and right children respective 阅读全文

摘要： Given two integers A and B, return any string S such that: S has length A + B and contains exactly A 'a' letters, and exactly B 'b' letters; The subst 阅读全文

摘要： This problem was asked by Microsoft. A number is considered perfect if its digits sum up to exactly 10. Given a positive integer n, return the n-th pe 阅读全文

摘要： Given the root of a binary tree, each node has a value from 0 to 25 representing the letters 'a' to 'z': a value of 0 represents 'a', a value of 1 rep 阅读全文

摘要： This problem was asked by Google. On our special chessboard, two bishops attack each other if they share the same diagonal. This includes bishops that 阅读全文

摘要： Given a binary tree, find the length of the longest path where each node in the path has the same value. This path may or may not pass through the roo 阅读全文

摘要： This problem was recently asked by Google. Given a list of numbers and a number k, return whether any two numbers from the list add up to k. For examp 阅读全文

摘要： Given an array nums, there is a sliding window of size k which is moving from the very left of the array to the very right. You can only see the k num 阅读全文

摘要： This problem was asked by Google. Implement locking in a binary tree. A binary tree node can be locked or unlocked only if all of its descendants or a 阅读全文

摘要： Implement a trie with insert, search, and startsWith methods. Notice You may assume that all inputs are consist of lowercase letters a-z. Implement a 阅读全文