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Given an array where elements are sorted in ascending order, convert it to a height balanced BST. For this problem, a height-balanced binary tree is d 阅读全文
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Sort a linked list in O(n log n) time using constant space complexity. Example 1: Example 2: divide and conquer + merge sort，先找中点，断开，再merge time: O(nl 阅读全文
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Given a binary tree, find the lowest common ancestor (LCA) of two given nodes in the tree. According to the definition of LCA on Wikipedia: “The lowes 阅读全文
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Given a binary search tree (BST), find the lowest common ancestor (LCA) of two given nodes in the BST. According to the definition of LCA on Wikipedia 阅读全文
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Calculate the sum of two integers a and b, but you are not allowed to use the operator + and -. Example 1: Input: a = 1, b = 2 Output: 3 Example 2: In 阅读全文
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sort & comparator 各种排序方法总结 bit manipulation A summary: how to use bit manipulation to solve problems 阅读全文
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In an alien language, surprisingly they also use english lowercase letters, but possibly in a different order. The order of the alphabet is some permu 阅读全文
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Given a nested list of integers, return the sum of all integers in the list weighted by their depth. Each element is either an integer, or a list -- w 阅读全文
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Given a nested list of integers, return the sum of all integers in the list weighted by their depth. Each element is either an integer, or a list -- w 阅读全文
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You are given a data structure of employee information, which includes the employee's unique id, his importance value and his directsubordinates' id. 阅读全文