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Container With Most Water Given n non-negative integers a1, a2, ..., an, where each represents a point at coordinate (i, ai). n vertical lines are dra 阅读全文
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Reverse digits of an integer. Example1: x = 123, return 321Example2: x = -123, return -321 click to show spoilers. Have you thought about this? Here a 阅读全文
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The string "PAYPALISHIRING" is written in a zigzag pattern on a given number of rows like this: (you may want to display this pattern in a fixed font 阅读全文
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Given a string, find the length of the longest substring without repeating characters. Examples: Given "abcabcbb", the answer is "abc", which the leng 阅读全文
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You are given two non-empty linked lists representing two non-negative integers. The digits are stored in reverse order and each of their nodes contai 阅读全文
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Given an array of integers, return indices of the two numbers such that they add up to a specific target. You may assume that each input would have ex 阅读全文
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tag: 二叉树 思路: 最长距离一定是两个叶子节点之间的距离 ＝> 两个叶子节点必定以某个节点为根节点 ＝> 因此用DFS思路自底向上计算经过每一个节点的最长距离，取其最大值 以每个节点为根节点的最长距离 ＝ 左子树的高度＋右子树的高度 阅读全文