摘要： Given a binary tree, collect a tree's nodes as if you were doing this: Collect and remove all leaves, repeat until the tree is empty. Example:Given bi 阅读全文

摘要： Given a non-negative number represented as a singly linked list of digits, plus one to the number. The digits are stored such that the most significan 阅读全文

摘要： Assume you have an array of length n initialized with all 0's and are given k update operations. Each operation is represented as a triplet: [startInd 阅读全文

摘要： A string such as "word" contains the following abbreviations: Given a target string and a set of strings in a dictionary, find an abbreviation of this 阅读全文

摘要： 379. Design Phone Directory Design a Phone Directory which supports the following operations: Example: 阅读全文

摘要： (M) Permutations (M) Permutations II (M) Permutation Sequence (M) Palindrome Permutation II (M) Permutations (M) Permutations II (M) Permutation Seque 阅读全文

摘要： https://leetcode.com/problems/combination-sum-iii/ 用dfs枚举。 其他同类题： http://www.jiuzhang.com/solutions/search/?question=Combination+Sum 1. http://www.lin 阅读全文

摘要： ztr loves math http://acm.hdu.edu.cn/showproblem.php?pid=5675 显然：4 ^ n * (a + b) * (a -b) 阅读全文

摘要： 1. 反转链表 2. 实现HashMap的Put，Get操作 3. two sum 4. 给一个random函数能等概率生成0~4的5个随机数，利用这个函数来实现等概率随机生成0~6的7个数的随机数。 阅读全文

摘要： http://hihocoder.com/contest/hiho93/problem/1?sid=764530 提示：Eular质数筛法 提示：Eular质数筛法 小Hi：我们可以知道，任意一个正整数k，若k≥2，则k可以表示成若干个质数相乘的形式。Eratosthenes筛法中，在枚举k的每一个 阅读全文