摘要：
Givenn, how many structurally uniqueBST's(binary search trees) that store values 1...n?For example,Givenn= 3, there are a total of 5 unique BST's. 1... 阅读全文
摘要：
Given a string containing only digits, restore it by returning all possible valid IP address combinations.For example:Given"25525511135",return["255.2... 阅读全文
摘要：
message containing letters fromA-Zis being encoded to numbers using the following mapping:'A' -> 1'B' -> 2...'Z' -> 26Given an encoded message contain... 阅读全文
摘要：
题目：Given a strings1, we may represent it as a binary tree by partitioning it to two non-empty substrings recursively.Below is one possible representat... 阅读全文
摘要：
complete tree,except possibly the last, is completely filled, and all nodes in the last level are as far left as possible.from wiki本来在考虑最底层到底满不满，发现是通过... 阅读全文
摘要：
来说说看问题急躁，一开始就理所当然的想问的是overlapped area，实际上是total。脑子里一堆边界条件，看了ref觉得很简洁http://blog.csdn.net/foreverling/article/details/46411069public class Solution { ... 阅读全文
摘要：
典型的dfs题，建议在其他dfs之前做public class Solution { public ArrayList> combine(int n, int k) { ArrayList> res = new ArrayList>(); if(nn) return... 阅读全文
摘要：
public class Solution { public int minDistance(String word1, String word2) { if(word1==null||word1.length()==0) return word2.length(); ... 阅读全文
摘要：
几个corner cases要清楚refhttp://www.cnblogs.com/springfor/p/3869666.html引用一个用法注意“判断字符串相等与否要用.equals()，因为是引用类型。要注意split函数是可以split出空字符的，例如：//b/ 会被split结果为[""... 阅读全文
摘要：
public class Solution { public int climbStairs(int n) { int[] res =new int[n+3]; // 因为如果n<3,至少希望把前三个位置做出来 res[0] = 0; res[1]... 阅读全文