摘要：Write a program to find the node at which the intersection of two singly linked lists begins. For example, the following two linked lists: 求两个链表开始重合的地 阅读全文

摘要：Design a stack that supports push, pop, top, and retrieving the minimum element in constant time. push(x) -- Push element x onto stack. pop() -- Remov 阅读全文

摘要：Given a string, determine if it is a palindrome, considering only alphanumeric characters and ignoring cases. For example,"A man, a plan, a canal: Pan 阅读全文

摘要：Given an array of integers that is already sorted in ascending order, find two numbers such that they add up to a specific target number. The function 阅读全文

摘要：Say you have an array for which the ith element is the price of a given stock on day i. If you were only permitted to complete at most one transaction 阅读全文

摘要：Given an index k, return the kth row of the Pascal's triangle. For example, given k = 3,Return [1,3,3,1]. Note:Could you optimize your algorithm to us 阅读全文

摘要：Given numRows, generate the first numRows of Pascal's triangle. For example, given numRows = 5,Return 思路：动态规划，前面的构建出来了，后面根据某种关系也就可以构建出来。 这个要根据前一行来构建下一 阅读全文

摘要：Given a binary tree and a sum, determine if the tree has a root-to-leaf path such that adding up all the values along the path equals the given sum. F 阅读全文

摘要：Given a binary tree, determine if it is height-balanced. For this problem, a height-balanced binary tree is defined as a binary tree in which the dept 阅读全文

摘要：Given an array where elements are sorted in ascending order, convert it to a height balanced BST. For this problem, a height-balanced binary tree is d 阅读全文

摘要：Given a binary tree, return the bottom-up level order traversal of its nodes' values. (ie, from left to right, level by level from leaf to root). For 阅读全文

摘要：判断一棵二叉树是否为对称的树。如 观察上面的树可以看出：左子树的右子树等于右子树的左子树，左子树的左子树等于右子树的右子树。 首先可以使用递归。递归容易理解 再是可以使用迭代，不用递归。 思路就是向遍历一样，每一层比较，但是不输出，只是在遍历过程中比较。使用广度优先遍历。因为要比较，所以一次取出两个 阅读全文

摘要：Example 2: Example 3: 判断两个二叉树是否相等。 一：使用递归。 二：根据遍历出来的顺序，但是由于遍历右左子树可能有一个为空，会影响结果。 class Solution { StringBuilder sb1=new StringBuilder(); StringBuilder 阅读全文

摘要：Given two sorted integer arrays nums1 and nums2, merge nums2 into nums1 as one sorted array. Note:You may assume that nums1 has enough space (size tha 阅读全文

摘要：删除链表中重复的节点，但是重复的节点得留一个 Given 1->1->2, return 1->2.Given 1->1->2->3->3, return 1->2->3. 阅读全文

摘要：You are climbing a stair case. It takes n steps to reach to the top. Each time you can either climb 1 or 2 steps. In how many distinct ways can you cl 阅读全文

摘要：自己设计函数，实现求根号。x是非负整数。 Input: 8 Output: 2 当开出根号后有小数，则省略小数部分。。 思路：只要找到一个数a，a*a<=x而且(a+1)*(a+1)>x，则a就是开根号后的结果。 这里要注意：a*a因为<=x,不会溢出，但是(a+1)*(a+1)则可能会导致溢出。一 阅读全文

摘要：Given two binary strings, return their sum (also a binary string). For example,a = "11"b = "1"Return "100". 我们可以用StringBuiler来存放相加以后的结果，然后在reverse()就行 阅读全文

摘要：Given a roman numeral, convert it to an integer. Input is guaranteed to be within the range from 1 to 3999. 将罗马数字转成阿拉伯数字。需要了解两者对应关系。 罗马数字共有7个，即I（1）、V（ 阅读全文

摘要：转载自：http://blog.csdn.net/lnho2015/article/details/50962989 以下是我个人做题过程中的一些体会： 1. LeetCode的题库越来越大，截止到目前，已经有321个问题了。对于大多数人来说，没有时间也没有必要把所有题目都做一遍（时间充裕可以随意） 阅读全文