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题目链接 题目要求： Write an algorithm to determine if a number is "happy". A happy number is a number defined by the following process: Starting with any... 阅读全文
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1.Reverse Integer 题目链接 题目要求： Reverse digits of an integer. Example1:x = 123, return 321 Example2:x = -123, return -321 click to show spoilers.... 阅读全文
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题目链接 题目要求： Given a stringSand a stringT, count the number of distinct subsequences ofTinS. A subsequence of a string is a new string which is for... 阅读全文
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题目链接 题目要求： Given a strings1, we may represent it as a binary tree by partitioning it to two non-empty substrings recursively. Below is one possib... 阅读全文
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题目链接 题目要求： Given two wordsword1andword2, find the minimum number of steps required to convertword1toword2. (each operation is counted as 1 step.) ... 阅读全文
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题目链接 题目要求： Given a string containing only digits, restore it by returning all possible valid IP address combinations. For example: Given"2552551... 阅读全文
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题目链接 题目要求： Given a string, determine if it is a palindrome, considering only alphanumeric characters and ignoring cases. For example, "A man, a ... 阅读全文
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1.Unique Binary Search Trees 题目链接 题目要求： Givenn, how many structurally uniqueBST's(binary search trees) that store values 1...n? For example, Gi... 阅读全文
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之所以将这三道题放在一起，是因为这三道题非常类似。 1.Minimum Path Sum 题目链接 题目要求： Given amxngrid filled with non-negative numbers, find a path from top left to bottom rig... 阅读全文
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题目链接 题目要求： Find the total area covered by two rectilinear rectangles in a 2D plane. Each rectangle is defined by its bottom left corner and top r... 阅读全文