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We have a list of points on the plane. Find the K closest points to the origin (0, 0). (Here, the distance between two points on a plane is the Euclid 阅读全文
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A complete binary tree is a binary tree in which every level, except possibly the last, is completely filled, and all nodes are as far left as possibl 阅读全文
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In a binary tree, the root node is at depth 0, and children of each depth k node are at depth k+1. Two nodes of a binary tree are cousins if they have 阅读全文
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Given a string containing just the characters '(', ')', '{', '}', '[' and ']', determine if the input string is valid. An input string is valid if: No 阅读全文
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Given a linked list, determine if it has a cycle in it. To represent a cycle in the given linked list, we use an integer pos which represents the posi 阅读全文
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Given an array of integers nums, sort the array in ascending order. Example 1: Example 2: Note: 参考 https://www.cnblogs.com/fatttcat/p/10058544.html M1 阅读全文
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The Fibonacci numbers, commonly denoted F(n) form a sequence, called the Fibonacci sequence, such that each number is the sum of the two preceding one 阅读全文
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We are playing the Guess Game. The game is as follows: I pick a number from 1 to n. You have to guess which number I picked. Every time you guess wron 阅读全文
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2. Add Two Numbers - Medium topics: linked list, math solution 3. Longest Substring Without Repeating Characters - Medium topics: hash table, two poin 阅读全文
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Sliding Window Problems 76. Minimum Window Substring 438. Find All Anagrams in a String 30. Substring with Concatenation of All Words 3. Longest Subst 阅读全文