随笔分类 - LeetCode
摘要：给你一个整数 x ，如果 x 是一个回文整数，返回 true ；否则，返回 false 。 回文数是指正序（从左向右）和倒序（从右向左）读都是一样的整数。 例如，121 是回文，而 123 不是。 示例 1： 输入：x = 121 输出：true 示例 2： 输入：x = -121 输出：false
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摘要：一、爬楼梯 假设你正在爬楼梯。需要 n 阶你才能到达楼顶。 每次你可以爬 1 或 2 个台阶。你有多少种不同的方法可以爬到楼顶呢？ 注意：给定 n 是一个正整数。 示例 1： 输入： 2 输出： 2 解释： 有两种方法可以爬到楼顶。 1 阶 + 1 阶 2 阶 示例 2： 输入： 3 输出： 3 解
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摘要：X is a good number if after rotating each digit individually by 180 degrees, we get a valid number that is different from X. Each digit must be rotate
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摘要：A zero indexed array A consisting of N numbers is given. A slice of that array is any pair of integers (P, Q) such that 0 A = [1, 2, 3, 4] return: 3,
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摘要：Assume you are an awesome parent and want to give your children some cookies. But, you should give each child at most one cookie. Each child i has a g
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摘要：Given a fixed length array arr of integers, duplicate each occurrence of zero, shifting the remaining elements to the right. Note that elements beyond
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摘要：Given an n ary tree, return the level order traversal of its nodes' values. (ie, from left to right, level by level). For example, given a 3 ary tree:
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摘要：Given the root node of a binary search tree (BST) and a value to be inserted into the tree, insert the value into the BST. Return the root node of the
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摘要：You're given strings J representing the types of stones that are jewels, and S representing the stones you have. Each character in Sis a type of stone
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摘要：Given an integer array with no duplicates. A maximum tree building on this array is defined as follow: The root is the maximum number in the array. Th
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摘要：Given a string, find the length of the longest substring without repeating characters. Examples: Given , the answer is , which the length is 3. Given
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摘要：Write a SQL query to rank scores. If there is a tie between two scores, both should have the same ranking. Note that after a tie, the next ranking num
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摘要：Given a positive integer, output its complement number. The complement strategy is to flip the bits of its binary representation. Note: Example 1: Exa
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摘要：与树的前中后序遍历的DFS思想不同，层次遍历用到的是BFS思想。一般DFS用递归去实现（也可以用栈实现），BFS需要用队列去实现。 层次遍历的步骤是： 1.对于不为空的结点，先把该结点加入到队列中 2.从队中拿出结点，如果该结点的左右结点不为空，就分别把左右结点加入到队列中 3.重复以上操作直到队列
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摘要：Given a string containing only digits, restore it by returning all possible valid IP address combinations. For example:Given "25525511135", return ["2
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摘要：Given a binary tree, return thepreordertraversal of its nodes' values.For example:Given binary tree{1,#,2,3}, 1 \ 2 / 3return[1,2,3].Not...
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摘要：Given an array ofnintegers wheren> 1,nums, return an arrayoutputsuch thatoutput[i]is equal to the product of all the elements ofnumsexceptnums[i].Solv...
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摘要：You are playing the following Nim Game with your friend: There is a heap of stones on the table, each time one of you take turns to remove 1 to 3 ston...
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摘要：Given a binary search tree (BST), find the lowest common ancestor (LCA) of two given nodes in the BST.According to thedefinition of LCA on Wikipedia: ...
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摘要：Invert a binary tree. 4 / \ 2 7 / \ / \1 3 6 9to 4 / \ 7 2 / \ / \9 6 3 1Trivia:This problem was inspired bythis...
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