linxiong1991

摘要： Two elements of a binary search tree (BST) are swapped by mistake.Recover the tree without changing its structure.Note:A solution using O(n) space is ... 阅读全文

摘要： Given an array of non-negative integers, you are initially positioned at the first index of the array.Each element in the array represents your maximu... 阅读全文

摘要： The set[1,2,3,…,n]contains a total ofn! unique permutations.By listing and labeling all of the permutations in order,We get the following sequence (ie... 阅读全文

摘要： Given a 2D board and a word, find if the word exists in the grid.The word can be constructed from letters of sequentially adjacent cell, where "adjace... 阅读全文

摘要： Given a collection of integers that might contain duplicates,nums, return all possible subsets.Note:Elements in a subset must be in non-descending ord... 阅读全文

摘要： 1. 先序遍历public void preorder(TreeNode root) { if(root == null) return; Stack stack = new Stack(); while(true) { if(root... 阅读全文

摘要： Count the number of prime numbers less than a non-negative number,n题意：求小于n的所有素数的个数。思路：1. 范围在1~n-1，求先把2的倍数删除，再把3的倍数删除，再把5的倍数删除。。。每次都把集合中最小元素的倍数删除，多次循环之... 阅读全文

摘要： 最近在看《Java编程思想》的第17章时，发现集合的继承关系中缺了Queue的类图，因此准备把图补上。另外，在绘制的过程中只保留了常用的集合对象，使整个继承看起来比较简洁。如果有错误，请大家指出。 阅读全文

摘要： Implementatoito convert a string to an integer.Hint:Carefully consider all possible input cases. If you want a challenge, please do not see below and ... 阅读全文

摘要： Given two integers representing the numerator and denominator of a fraction, return the fraction in string format.If the fractional part is repeating,... 阅读全文